2023 USDA Zone Map for Florida

[RedRabbit]

[RedRabbit]

Here's 2012 for reference:

[flplantguy]

I think the biggest changes are urban heat induced and a lack of the major advective events leading to the higher zones, plus more detail for places with sublety like inland lakes.  Now south of I4 is all zone 10 except colder spots, and it looks like they removed the 9A near archbold too.  It's the frequency getting less, not that the big drops don't happen at all. 

[RedRabbit]

Initial thoughts on the new map:

• Pretty good overall. 10a is the new 9b in Florida, but it was called for given the data. It doesn't change what you can/can't plant.
• Glad to see Orlando and Lakeland at 10a in the new map, I wasn't sure what would happen with them. I’m not happy to see them in the same zone as Siesta Key and Vero Beach, but there were bound to be some issues like this.
• 10a terminating in Daytona makes sense, but I don't like coastal Volusia and coastal Brevard in the same zone as the climate is just too different. Interestingly there's a slither of 10b in Brevard, probably thanks the Patrick AFB's data. 
• I'm somewhat surprised 9b went into SE Georgia, and even SC evidently. Glad to see some of the panhandle getting 9b too!
• East of Orlando should be 9b, but I was expecting that area to be overstated in the new map.
• 10b is way overstated in Pinellas County. Only immediate coastal areas are really that warm. 
• I'm glad to see 10b in NW Manatee, it's time!
• I'm very surprised, but happy to see Captiva and a portion of Sanibel in z11. I've speculated for awhile that may be the case, and it seems USDA agrees now.
• 10b in SW Sarasota County and Charlotte County is overstated. 10b terminates around Venice on the immediate coast according to the new map, which is debatable at best. It's blatantly wrong to call mainland Englewood/Rotunda 10b. 10b in SE Florida looks pretty good.
• z11 looks pretty good in South Florida.
• Key West seems to have been robbed of getting z12a.

 

Edited November 14, 2023 by RedRabbit

[PalmTreeDude]

Interesting! Cool to see them finally give it an update. I guess I'm "officially" in solid 7b here in Virginia now. 

Edited November 14, 2023 by PalmTreeDude
Added Text

[Looking Glass]

I had to drive twice in the past month from here to Vero Beach.  It’s amazing to see the changes in vegetation over two hours and one full Ag Zone.  You kind of go from predominantly tropical vegetation, to a more mixed assortment.  More of the native palmate palms and you see past cold damage on the coconuts and other 10b+ stuff, and they start to become a more rare and beat up.   I think the new changes do support what we see growing in regular folks and collectors yards. 

[Jimbean]

1 hour ago, RedRabbit said:

Initial thoughts on the new map:

• Pretty good overall. 10a is the new 9b in Florida, but it was called for given the data. It doesn't change what you can/can't plant.
• Glad to see Orlando and Lakeland at 10a in the new map, I wasn't sure what would happen with them. I’m not happy to see them in the same zone as Siesta Key and Vero Beach, but there were bound to be some issues like this.
• 10a terminating in Daytona makes sense, but I don't like coastal Volusia and coastal Brevard in the same zone as the climate is just too different. Interestingly there's a slither of 10b in Brevard, probably thanks the Patrick AFB's data. 
• I'm somewhat surprised 9b went into SE Georgia, and even SC evidently. Glad to see some of the panhandle getting 9b too!
• East of Orlando should be 9b, but I was expecting that area to be overstated in the new map.
• 10b is way overstated in Pinellas County. Only immediate coastal areas are really that warm. 
• I'm glad to see 10b in NW Manatee, it's time!
• I'm very surprised, but happy to see Captiva and a portion of Sanibel in z11. I've speculated for awhile that may be the case, and it seems USDA agrees now.
• 10b in SW Sarasota County and Charlotte County is overstated. 10b terminates around Venice on the immediate coast according to the new map, which is debatable at best. It's blatantly wrong to call mainland Englewood/Rotunda 10b. 10b in SE Florida looks pretty good.
• z11 looks pretty good in South Florida.
• Key West seems to have been robbed of getting z12a.

 

Those are pretty much my thoughts as well.  Otherwise this map really needs to be taken with a grain of salt.  I understand why this map looks the way it does but it defeats the purpose of being a guide to what is hardy and where.

[RedRabbit]

I noticed something really interesting about this map... They're overrating potions of Central Florida and Pinellas County thanks to UHI in Orlando/Lakeland and an extremely favorable weather station siting in St. Pete. They're making some bad assumptions from the data so these errors make sense and are predictable. 

What I find interesting though is Western Manatee County in z10b and part of Lee County in z11a. Those ratings don't appear to be consistent with the data from the nearest weather stations, but it's very consistent with a theory I've had about Florida microclimates. So it looks like their new map is a blend of weather station data combined with some sort of predictive modeling based on local geographic features. 

Despite some flaws, I give them a ton of credit for their calls on Western Manatee County and Lee County. I'll review their methodology when I get some time. 

[Jimbean]

6 minutes ago, RedRabbit said:

I noticed something really interesting about this map... They're overrating potions of Central Florida and Pinellas County thanks to UHI in Orlando/Lakeland and an extremely favorable weather station siting in St. Pete. They're making some bad assumptions from the data so these errors make sense and are predictable. 

What I find interesting though is Western Manatee County in z10b and part of Lee County in z11a. Those ratings don't appear to be consistent with the data from the nearest weather stations, but it's very consistent with a theory I've had about Florida microclimates. So it looks like their new map is a blend of weather station data combined with some sort of predictive modeling based on local geographic features. 

Despite some flaws, I give them a ton of credit for their calls on Western Manatee County and Lee County. I'll review their methodology when I get some time. 

I have some serious issues with the map for the east section of Florida.  Sebastian and Fort Peirce Inlets should also be 10A/10B, in addition to Patrick Space Force Base.  Seeing Bithlo in the same zone as Fort Peirce also grinds my gears.  East Orange county and any part interior of Volusia as zone 10A is more than a stretch, it's laughable.  It looks as though no one who put this map together as ever driven around east central Florida. 

[RedRabbit]

20 minutes ago, Jimbean said:

I have some serious issues with the map for the east section of Florida.  Sebastian and Fort Peirce Inlets should also be 10A/10B, in addition to Patrick Space Force Base.  Seeing Bithlo in the same zone as Fort Peirce also grinds my gears.  East Orange county and any part interior of Volusia as zone 10A is more than a stretch, it's laughable.  It looks as though no one who put this map together as ever driven around east central Florida. 

Trust me, I get it and I agree. I expected this though due lack of data in east Orange so they’re just assuming it’s the same the closest coastal or urban weather stations. I gave them credit where they seemed to diverge from that in W Manatee and Lee.

I think what’s going on here is their model takes into account water and elevation, but lacks a population density input to account for urban heating. It sees Orlando is 10a and can’t tell why so it assumes the whole area is just that warm and fills in the east Orange data blindspot as z10.

By the way, zoom in on coastal Brevard, there is a small section that’s 10b.

Edited November 14, 2023 by RedRabbit

[Jimbean]

25 minutes ago, RedRabbit said:

Trust me, I get it and I agree. I expected this though due lack of data in east Orange so they’re just assuming it’s the same the closest coastal or urban weather stations. I gave them credit where they seemed to diverge from that in W Manatee and Lee.

I think what’s going on here is their model takes into account water and elevation, but lacks a population density input to account for urban heating. It sees Orlando is 10a and can’t tell why so it assumes the whole area is just that warm and fills in the east Orange data blindspot as z10.

By the way, zoom in on coastal Brevard, there is a small section that’s 10b.

I saw that 10A/10B around Patrick Space Force Base.  If the weather station at Patrick showed a 30 year average minimum in the upper 30's, then why not other parts of the barrier islands south of that also weren't classified as such?  There's a section of the barrier island in Indian River county that doesn't have as much insulation from the Indian River Lagoon, otherwise areas to the north and south are practically the same as Patrick, Fort Peirce Inlet arguably a bit warmer in fact.

It's not like they don't know any better either.  Someone needed to look at this before it was published.  These people should know all about urban heat islands and not just go by what a weather station is doing in one place, just using a bit of logic these people should have been able to extrapolate that data point and predicted a trend. 

Edited November 14, 2023 by Jimbean

[flplantguy]

If they do the online presentation tomorrow still they might explain the methodology behind it all.  I think part of it is satellite readings on radiational freezes, I have seen a few analysis using them before, and advective is easy to do.

[kinzyjr]

4 hours ago, RedRabbit said:

Initial thoughts on the new map:

• Pretty good overall. 10a is the new 9b in Florida, but it was called for given the data. It doesn't change what you can/can't plant.
• Glad to see Orlando and Lakeland at 10a in the new map, I wasn't sure what would happen with them. I’m not happy to see them in the same zone as Siesta Key and Vero Beach, but there were bound to be some issues like this.
• 10a terminating in Daytona makes sense, but I don't like coastal Volusia and coastal Brevard in the same zone as the climate is just too different. Interestingly there's a slither of 10b in Brevard, probably thanks the Patrick AFB's data. 
• I'm somewhat surprised 9b went into SE Georgia, and even SC evidently. Glad to see some of the panhandle getting 9b too!
• East of Orlando should be 9b, but I was expecting that area to be overstated in the new map.
• 10b is way overstated in Pinellas County. Only immediate coastal areas are really that warm. 
• I'm glad to see 10b in NW Manatee, it's time!
• I'm very surprised, but happy to see Captiva and a portion of Sanibel in z11. I've speculated for awhile that may be the case, and it seems USDA agrees now.
• 10b in SW Sarasota County and Charlotte County is overstated. 10b terminates around Venice on the immediate coast according to the new map, which is debatable at best. It's blatantly wrong to call mainland Englewood/Rotunda 10b. 10b in SE Florida looks pretty good.
• z11 looks pretty good in South Florida.
• Key West seems to have been robbed of getting z12a.

My take was pretty similar to yours and @Jimbean's in regard to the inland areas on the I-4 corridor.  There are spots like downtown Lakeland, chain-of-lakes Winter Haven, and the lake and concrete modified areas from Sanford down to St. Cloud that are protected enough to move above the 10a mark, but in general, areas outside of that influence should be some flavor of  9b.  Eastern Orange county and inland Volusia are two of the usual areas where we all three would draw the zone lines differently based on Wunderground observations and just driving through the area and noting the damage or death after a cold snap.  Lake Monroe is the border for non-coastal high 9b/low 10a when I draw my Google Maps.

Your first bulletpoint sums it up pretty well for our region.

Overall, the new USDA map is a bit more generous than the various maps on our Make Your Own Zone Map thread.

[Jimbean]

This is the worst map that the USDA has ever produced.  I'm guessing out of laziness, it doesn't take microclimate principles and simple logic into consideration.  If I were the head of the USDA, I'd send this map right back to whoever produced it.  These maps are supposed to be a guide.  Can you imagine being close to I-95, west of New Smyrna Beach and being told that foxtails and royals are hardy long term?  In Titusville you would have to be right on the Indian River for those palms to be anywhere near hardy, and as soon as you head inland they really become a zone push. 

Edited November 15, 2023 by Jimbean

[SeanK]

Good news for the panhandle.

With the increases, why haven't we seen any islands sink?

[flplantguy]

I think some of it is laziness and they did not prioritize areas with fewer people. That happened with Pasco county before and now they have it better than it was.  I think those areas are an urban 10a and they just don't care about conservation areas and open rangeland that's more 9b.

[RedRabbit]

I've been living in Zone 10 for about 24 hours now and I must say it's great. 😎

• I put in an order to Floribunda for every Euterpe and Neoveitchia they've got.
• Removed all my Sabals and Phoenix, they have no place in a z10 garden.
• Cleared my closet of jackets, long pants, long sleeved shirts, and underwear (why not? 😉 ). 
• My property value has increased 30% overnight (who doesn't want to be in z10?).
• Not only do I live in a better zone, I believe I am also a better person now. (And you're a worse person if you don't live in z10.)

Also, to express my feelings about my new zone, I've taken to music:

Hello, it's me

I was wondering if after all these years you'd like to see me

To chat about palm trees

They say that time's supposed to heal ya, but I've been busy planting

Hello, can you hear me? I'm in Zone 10 dreaming about palm trees swaying free

When we were just a tad frosty, but now it's a tropical jubilee

I've forgotten how it felt before the palms lined our street

There's such a difference in our zones

And a million miles, now surrounded by coconut piles!

(Chorus)

Hello from Zone 10

I must've grown a thousand palms

To tell you I've upgraded from the chill of Zone 9

But when I call, your garden's still stuck above that temperate line

Hello from the tropics outside

At least I can say that I've tried

To tell you I'm sorry for leaving your cooler zone

But it don't matter, it clearly doesn't freeze here anymore

(Verse 2)

Hello, how's your soil?

It's so typical of me to talk about hardiness, oh the toil

I hope that you've thawed out, no longer in that chilly turmoil

Did you ever make it out of that town where frostbite was the only term?

It's no secret that Zone 9 and I

Have run out of time, while Zone 10 is sublime

(Chorus)

Hello from Zone 10

I must've grown a thousand vines

To tell you I'm loving the sunshine, and my palms are reaching new heights

But when I call, your garden's still in the shiver zone

Hello from the warmth outside

At least I can say that I've tried

To tell you I'm sorry for leaving your cooler zone

But it don't matter, since it clearly doesn't freeze here anymore, hooray for warmth!

(Bridge)

Ooh (lows, lows, lows, lows), no more chilly woes (Highs, highs, highs, highs), just tropical highs Ooh (lows, lows, lows, lows), no more winter throes (Highs, highs, highs, highs), just sunny skies

(Chorus)

Hello from Zone 10

I must've grown a thousand vines

To tell you I'm living where the weather is sublime

But when I call, your garden's still above the frost line

Hello from the warmth outside

At least I can say that I've tried

To tell you I'm sorry for leaving your cooler zone

But it don't matter, since it clearly doesn't freeze here anymore, cheers to Zone 10!

 

 

 

 

 

"

Edited November 15, 2023 by RedRabbit

[flplantguy]

Can mature pothos vines on oak trees be a zone indicator?  Like 10a or "warm 9b"?  I think the majority of the peninsula is in that designation of freezes being very light. So the average comes out to 30 or 32, and it still is freezing that blocks certain tropical plants from living long-term yet is called 10a.  Then across the street you could have the average become 29 and be a 9b.  It's all cool as a data point but it's only one. My near 10a location has way more cool nights than one further south, then add in other factors and the zone designation is really a "base map" for planting.  Much of this area is on the line between 10A and 9b and there are pothos vines everywhere on trees including a very old one in a neighbors yard I just noticed.

[Jimbean]

 

13 minutes ago, flplantguy said:

Can mature pothos vines on oak trees be a zone indicator?  Like 10a or "warm 9b"?  I think the majority of the peninsula is in that designation of freezes being very light. So the average comes out to 30 or 32, and it still is freezing that blocks certain tropical plants from living long-term yet is called 10a.  Then across the street you could have the average become 29 and be a 9b.  It's all cool as a data point but it's only one. My near 10a location has way more cool nights than one further south, then add in other factors and the zone designation is really a "base map" for planting.  Much of this area is on the line between 10A and 9b and there are pothos vines everywhere on trees including a very old one in a neighbors yard I just noticed.

 

In my opinion, seeing pothos vines has a lot to do with living in residential areas, but I would say seeing them grow up on trees is perhaps a 9B indicator. 

Seeing large ficus trees, plumaria trees, mature coconuts, etc. are indicators of zone 10A

Edited November 15, 2023 by Jimbean

[JJPalmer]

Not Florida related, but surprised no one brought up the *tiniest* sliver of 10b in far SE Louisiana or the 10a bit near New Orleans.  Can't wait to see the debate on those locations.

[flplantguy]

15 minutes ago, Jimbean said:

 

 

In my opinion, seeing pothos vines has a lot to do with living in residential areas, but I would say seeing them grow up on trees is perhaps a 9B indicator. 

Seeing large ficus trees, plumaria trees, mature coconuts, etc. are indicators of zone 10A

My area is not so developed so it's hard to find indicator plants unless they are invasive like Brazilian peppers.  We are surrounded by wetlands and open space outside with the larger lots, and then it's far enough away it's not the same area really.  The people here generally don't garden or it's farming veggies, so I have one traveler "palm" next street over, a new (so useless) Norfolk pine which is hardier anyway, the Brazilian peppers and a clump of Australian pine, and some new sea grapes.  They don't defoliate every winter and only this past one harmed the traveler, but it seems they take chill damage so it's not like further south.

[flplantguy]

18 minutes ago, JJPalmer said:

Not Florida related, but surprised no one brought up the *tiniest* sliver of 10b in far SE Louisiana or the 10a bit near New Orleans.  Can't wait to see the debate on those locations.

I saw that and said "huh?" to myself but I don't know lot about that area to have an opinion.  There are still oddities that's for sure.

[JJPalmer]

20 hours ago, RedRabbit said:

I'll review their methodology when I get some time. 

I'm curious about the methodology as well, as in Colorado the map does not do a great job of showing the 'cold sinks' across the state.   Jefferson, CO hit -24f a couple of weeks ago during a fairly typical October cold snap, but they're listed at 5a (-20f to -15f) and will routinely fall below -25f.  Peter Sinks in Utah hit -60f last year and hits -40f several times annually and is listed as 4a.  Both Jefferson and Peter Sinks have reliable, publicly available weather and climatology data.   If the resolution on the map is sufficient to include a single dot of 10b in Louisiana, I'm surprised these aren't better represented. 

As always - no one knows the climate of an area better than the locals, and expecting the USDA to perfectly map the climates across the entirety of the country is a tall ask.  Though if one paid me, I'd certainly like to make an attempt. 

[JJPalmer]

1 minute ago, flplantguy said:

I saw that and said "huh?" to myself but I don't know lot about that area to have an opinion.  There are still oddities that's for sure.

Prior to the hurricane, far SE LA had mature royals and a few other z10 palms growing; harder to find example pics now.  Don't doubt that area is 10a - though not as confident in DTNO.  

[Jimbean]

I think this is what a somewhat more reasonable person would have done with their 2023 data.  This is a rough sketch, as if an adult was to interpret what a child was trying to get at.

[RFun]

On 11/14/2023 at 2:40 PM, flplantguy said:

I think the biggest changes are urban heat induced and a lack of the major advective events leading to the higher zones, plus more detail for places with sublety like inland lakes.  Now south of I4 is all zone 10 except colder spots, and it looks like they removed the 9A near archbold too.  It's the frequency getting less, not that the big drops don't happen at all. 

The urban heat thing is very real.  Florida is a prime example of that.  If anything, urban heat is often overlooked.  That can make a big difference in whether you see frost on the ground in many areas or not.  Often times, the urban areas will have no ground frost (or very spotty frost), while the rural areas around will have frost covering the ground.

Edited November 15, 2023 by RFun

[RFun]

2 hours ago, JJPalmer said:

Not Florida related, but surprised no one brought up the *tiniest* sliver of 10b in far SE Louisiana or the 10a bit near New Orleans.  Can't wait to see the debate on those locations.

That sliver of 10b makes sense.  Water plays a big role in that. 

[kinzyjr]

9 hours ago, RedRabbit said:

I've been living in Zone 10 for about 24 hours now and I must say it's great. 😎

• I put in an order to Floribunda for every Euterpe and Neoveitchia they've got.
• Removed all my Sabals and Phoenix, they have no place in a z10 garden.
• Cleared my closet of jackets, long pants, long sleeved shirts, and underwear (why not? 😉 ). 
• My property value has increased 30% overnight (who doesn't want to be in z10?).
• Not only do I live in a better zone, I believe I am also a better person now. (And you're a worse person if you don't live in z10.)

Also, to express my feelings about my new zone, I've taken to music:

This gave me a good chuckle.  Glad my location barely made the cut for the promotion to "better person territory", literally by a 5 minute jaunt down the highway.

 We'll look forward to your karaoke rendition of your new hit single this weekend in Ybor City 😆

Called my realtor and told them to add "USDA Zone 10a, but only minutes from 9b if you need to cool off" to the listing.  Their cutoff was reasonably close the UHI cutoff I typically use on maps - Harden Blvd/Sikes Blvd/Kathleen Rd.

I guess this sign was ahead of its time:

 

 

11 hours ago, Jimbean said:

If I were the head of the USDA, I'd send this map right back to whoever produced it.

To be a fly on the wall when they walked that map in and handed it to you for review. 😬 

If you need a letter of recommendation, just reach out and bring a few of us with you.  We'll approve zone maps American Idol style.

[JLM]

Im officially 9a now, although keeping 8b/9a because i can definitely still get 8b winters. Interesting thing to note is that Gulf Breeze and Pensacola Beach are now 9b. Feels weird saying that.
 

[Aceraceae]

They overlook or omit the tiny bit of 12a for Key West with a mean minimum of 50.1 F for 1991 to 2020. The brush the whole Keys as 11b just like before. 

[Eric in Orlando]

Why do they only use 30 years of data? Why not use all the data for averages, going back to 1960 or before?  Now the data does not include the 3 big freezes of the 1980s. I would think the more data you have then there is a much better representation of long term climate averages.

I would love to see zone maps from the late 1700s/early 1800s when there was obviously a very warm cycle; mature Royal Palms growing wild along the St. John's River near Astor (Volusia County), citrus groves from Jacksonville FL to Charleston SC and groves of the tender West Indian race of avocadoes and mangos at St. Augustine. Then the 1835 freeze ended that. 

[RFun]

13 minutes ago, Eric in Orlando said:

Why do they only use 30 years of data? Why not use all the data for averages, going back to 1960 or before?  Now the data does not include the 3 big freezes of the 1980s. I would think the more data you have then there is a much better representation of long term climate averages.

I would love to see zone maps from the late 1700s/early 1800s when there was obviously a very warm cycle; mature Royal Palms growing wild along the St. John's River near Astor (Volusia County), citrus groves from Jacksonville FL to Charleston SC and groves of the tender West Indian race of avocadoes and mangos at St. Augustine. Then the 1835 freeze ended that. 

I prefer the longer time frames myself just to cause a little less confusion that will be inevitable.  And you are right, they had citrus groves much further north.

[RedRabbit]

15 hours ago, kinzyjr said:

This gave me a good chuckle.  Glad my location barely made the cut for the promotion to "better person territory", literally by a 5 minute jaunt down the highway.

 We'll look forward to your karaoke rendition of your new hit single this weekend in Ybor City 😆

Called my realtor and told them to add "USDA Zone 10a, but only minutes from 9b if you need to cool off" to the listing.  Their cutoff was reasonably close the UHI cutoff I typically use on maps - Harden Blvd/Sikes Blvd/Kathleen Rd.

I guess this sign was ahead of its time:

 

 

To be a fly on the wall when they walked that map in and handed it to you for review. 😬 

If you need a letter of recommendation, just reach out and bring a few of us with you.  We'll approve zone maps American Idol style.

ChatGPT has the best use cases, like making songs about living in z10. 😍

Good call on including z10 in your MLS listing, it’ll surely go for more. 👍
 

23 hours ago, JJPalmer said:

I'm curious about the methodology as well, as in Colorado the map does not do a great job of showing the 'cold sinks' across the state.   Jefferson, CO hit -24f a couple of weeks ago during a fairly typical October cold snap, but they're listed at 5a (-20f to -15f) and will routinely fall below -25f.  Peter Sinks in Utah hit -60f last year and hits -40f several times annually and is listed as 4a.  Both Jefferson and Peter Sinks have reliable, publicly available weather and climatology data.   If the resolution on the map is sufficient to include a single dot of 10b in Louisiana, I'm surprised these aren't better represented. 

As always - no one knows the climate of an area better than the locals, and expecting the USDA to perfectly map the climates across the entirety of the country is a tall ask.  Though if one paid me, I'd certainly like to make an attempt. 

Supposedly they’re going to release the data they used to make this chart. I’ve never messed with GIS data, but I might give geopandas a try in Python.

10b does seem weird for Louisiana. I think only a tiny sliver made it to 10a last time. Another weird thing is SC seems to have more z9b than GA does, and it’s not at all clear why. Topics for another thread I guess, I was hoping someone would start threads for CA and TX/LA. I don’t know their climates well enough to speculate over the new maps.

Edited November 16, 2023 by RedRabbit

[kinzyjr]

5 hours ago, Eric in Orlando said:

Why do they only use 30 years of data? Why not use all the data for averages, going back to 1960 or before?  Now the data does not include the 3 big freezes of the 1980s. I would think the more data you have then there is a much better representation of long term climate averages.

I would love to see zone maps from the late 1700s/early 1800s when there was obviously a very warm cycle; mature Royal Palms growing wild along the St. John's River near Astor (Volusia County), citrus groves from Jacksonville FL to Charleston SC and groves of the tender West Indian race of avocadoes and mangos at St. Augustine. Then the 1835 freeze ended that. 

The USDA Map used 1990-2020 data to be consistent with the new climate normals time frame.  My most current Google Zone Map uses 50 years of data from 1972-2022 as the basis of the zoning, but includes the average annual low for 30 years (AAL 30), 100 years (AAL 100), and all records (AAL ALL) for reference at each of the stations:

https://tinyurl.com/48pvem3y

I'd like to publish a 2023 version, but not sure when I'll finish scraping the data needed for the additional stations I want to include.

5 hours ago, RedRabbit said:

Another weird thing is SC seems to have more z9b than GA does, and it’s not at all clear why.

My anecdotal guess is that SC is still far enough south that the difference in longitude from Charleston down to Hilton Head plus the larger inlets provide enough water modification and distance away from continental weather coming from the west to east to give those areas some shelter vs. the relatively north to south coastline of GA.  Plus the large lakes inland may have an effect.

[RedRabbit]

1 hour ago, kinzyjr said:

The USDA Map used 1990-2020 data to be consistent with the new climate normals time frame.  My most current Google Zone Map uses 50 years of data from 1972-2022 as the basis of the zoning, but includes the average annual low for 30 years (AAL 30), 100 years (AAL 100), and all records (AAL ALL) for reference at each of the stations:

https://tinyurl.com/48pvem3y

I'd like to publish a 2023 version, but not sure when I'll finish scraping the data needed for the additional stations I want to include.

My anecdotal guess is that SC is still far enough south that the difference in longitude from Charleston down to Hilton Head plus the larger inlets provide enough water modification and distance away from continental weather coming from the west to east to give those areas some shelter vs. the relatively north to south coastline of GA.  Plus the large lakes inland may have an effect.

I’d be interested to see your updated map whenever it’s available (no rush.)

Let’s check on SC and GA this winter to see if SC is really warmer. I think the map got St. Simons right, with just a little 9b on East Beach and Sea Island. I’d be surprised if Hilton Head is really as warm as St. Simons.

[RFun]

7 hours ago, RedRabbit said:

I’d be interested to see your updated map whenever it’s available (no rush.)

Let’s check on SC and GA this winter to see if SC is really warmer. I think the map got St. Simons right, with just a little 9b on East Beach and Sea Island. I’d be surprised if Hilton Head is really as warm as St. Simons.

Truthfully, the 9b should extend all the way up the immediate Georgia coast.  The water is still playing a big role there.  The problem is that you don't have many weather stations that are hugging the coast in that area so the map isn't showing it.  The area from St. Simon's to Tybee (along the immediate coast) is unpopulated.  The area from St. Simon's south to the Jacksonville area should also be 9b because of the same reason.  The amount of south facing backyards in the Brunswick area that are also 9b is very high as well.  Lots of 9a in the front and 9b in the back type of stuff.  Really, its the same type of stuff many of you probably have when you are calling yourself 9a/9b or 5a/5b, etc.  Just something I always have in the back of my mind....

Edited November 17, 2023 by RFun

[BrunswickGuy]

8 hours ago, RFun said:

Truthfully, the 9b should extend all the way up the immediate Georgia coast.  The water is still playing a big role there.  The problem is that you don't have many weather stations that are hugging the coast in that area so the map isn't showing it.  The area from St. Simon's to Tybee (along the immediate coast) is unpopulated.  The area from St. Simon's south to the Jacksonville area should also be 9b because of the same reason.  The amount of south facing backyards in the Brunswick area that are also 9b is very high as well.  Lots of 9a in the front and 9b in the back type of stuff.  Really, its the same type of stuff many of you probably have when you are calling yourself 9a/9b or 5a/5b, etc.  Just something I always have in the back of my mind....

You are spot on with your assessment.  Jekyll and Cumberland Islands should be 9b but there are not a lot a weather stations I guess to document the temps there officially. I have lived in downtown Brunswick, GA for eight years - along the GA coast within 30 miles of the ocean, it is definitely warm 9a, but there are pockets of 9b for sure on the islands and warm microclimates (such as downtown Brunswick) on the mainland.  In eight winters here I have seen three 9a winters (22, 24, 24), two 9b winters (28, 28) and three 10a winters (30, 30, 32).  So yeah, I am on that 9a/9b line you talk about. 

[kinzyjr]

As a USDA Zone Map, it fits the definition of what they advertise - a map of average annual lows over 30 years with some issues using interpolation to "guess" in the blind spots.

For a horticultural guide, they should probably consider using @Jimbean's modification of starting zone 10a at an average annual low of 32F or 33F and adjust the other zones accordingly.

[sebastian_inlet]

On 11/14/2023 at 4:23 PM, Jimbean said:

I have some serious issues with the map for the east section of Florida.  Sebastian and Fort Peirce Inlets should also be 10A/10B, in addition to Patrick Space Force Base.  Seeing Bithlo in the same zone as Fort Peirce also grinds my gears.  East Orange county and any part interior of Volusia as zone 10A is more than a stretch, it's laughable.  It looks as though no one who put this map together as ever driven around east central Florida. 

You are right. Here is the minimum temperatures for Sebastian using this station which displays similar temperatures with what I have on a daily basis: 

https://www.wunderground.com/dashboard/pws/KFLSEBAS1/table/2023-01-22/2023-01-22/monthly

2023	39.1
2022	37.1
2021	36.9
2020	37.9
2019	40.5
2018	32.9
2017	41.7
2016	37.3
2015	35.1
2014	37.6
2013	39.5
2012	35.4

Average minimum temperature in the last 11 years for Sebastian is 37.58F which is clearly above the 35F threshold for 10B zone. The minimum of the minimums for this decade was 32.9, above freezing. I didn't have access to previous years of data for this weather station, and not sure they have it.  For Sebastian FL, I have the feeling they use the Melbourne airport station to estimate the temperatures.  That creates the impression that Sebastian is colder than what it is.  In reality, there is clear difference between the look of Melbourne, Sebastian and Vero Beach. It is hard to see coconuts in Melbourne, they are much more often in Sebastian, and Vero Beach and south.  In fact, the average temperature of January in this data set for Sebastian is 64.25F which is very close to the tropical threshold of 64.4 F.   

[Aceraceae]

Might have to move the phytogeography marker for the tropical climate designation up from Seabranch Preserve state park to Jensen beach or Vero beach, including coastal Port St. Lucie. Tropical requiring not only 18 C coldest month minimum (64.4 F, really 65 not 64 F), but also a 10b+ hardiness zone as 10a has way more frequent freezes.