Gulf Coastal/Inland Areas vs. Coastal Atlantic Areas (climate, warm, average)

[smithgn]

Hello everyone, I've come across something that has baffled me over the last few years and that is the similarities in gulf coastal/slightly inland areas such as Tallahassee, Pensacola, Mobile, Montgomery and Hattiesburg versus Atlantic coastal/slightly inland areas such as Wilmington, Myrtle Beach, Columbia, Charleston, Savannah and Jacksonville (FL). The main reason why I'm baffled by the similarities is due to the USDA plant hardiness zones that lists these gulf areas as being practically the exact same plant zones as the Atlantic coastal areas DESPITE these Atlantic areas being 3, sometimes 4 degrees farther north.
For instance, why is it that the 8B zone starts in the extreme lower parts of Mississippi and Alabama, when at the same time, the majority of Georgia and nearly half of South Carolina and parts of North Carolina have presences of 8B zones of up to nearly 5 degrees farther north compared to Mississippi and Alabama?

Other questions of note:

Jacksonville vs gulf areas: Why is Jacksonville rated a "guaranteed" 9A and the other areas on the gulf, rated as 8B when they are both on/near the water? Heck, the city of Jacksonville is not nestled RIGHT on the coast, it's still several miles inland. For example, look at Mobile, rated an 8B being compared to Jacksonville. Both relatively the same latitude and Mobile is right on the water.

Columbia vs Montgomery: Montgomery and south towards the Florida border is listed as 8A and Columbia is listed as an 8A. With Montgomery and the area south of it being nearly 3 degrees farther south than Columbia, why is it still listed as an 8A?

Cliff notes: Why the heck are the gulf areas not warmer due to their extreme southern latitude (relative to the United States) compared to the east coast that is farther north?

Please discuss, I'm all ears. And thanks in advance everyone.

[dexter2]

Hardiness is not about how warm or cold there is round the year. They tell you ranges of average lowest temperature throughout the years.
You've got currents and winds that comes from equatorial east making water and air near atlantic coast warmer in winters. So even if city is a little bit inland, from the perspective of Atlantic ocean they are still much closer then Mobile and others Gulf coast cities.

Examine this map: http://upload.wikimedia.org/wikipedi..._%28USA%29.jpg

But you have to remember that most of those informations are pretty general. Places have their own microclimates - that is why even if Mobile is listed as 8B, small covered areas very close to the water may have even 9B.

[tom77falcons]

Originally Posted by dexter2

Hardiness is not about how warm or cold there is round the year. They tell you ranges of average lowest temperature throughout the years.
You've got currents and winds that comes from equatorial east making water and air near atlantic coast warmer in winters. So even if city is a little bit inland, from the perspective of Atlantic ocean they are still much closer then Mobile and others Gulf coast cities.

Examine this map: http://upload.wikimedia.org/wikipedi..._%28USA%29.jpg

But you have to remember that most of those informations are pretty general. Places have their own microclimates - that is why even if Mobile is listed as 8B, small covered areas very close to the water may have even 9B.

The Gulf coastal areas are 9a, with some of the islands 9b (Dauphin Island, Horn Island, etc). Mobile is 9a, but the airport is way out in the hilly area west of the city in a cold hole. Also, the Appalachian Mts I believe block some of the cold air as well as northwest winds coming over the Great Lakes get more modified maybe than the air coming straight down thru the center of country to the Gulf Coast.

For Mobile, the airport closer to the city of Mobile is 9a (avg lowest winter temp of 22F), while the airport west of the city is 19F (8b).

[dexter2]

Yeah, you are right, I forgot about Appalachian mountain range that blocks arctic air masses in winter.