Wacky, but we are listed as zone 11?????? Trinidad?

Hey Folks this is a little odd.

I am tracking on Yahoo Weather our temperature to Miami's temperature, to see just when Miami goes down to those Winter lows.
Thus far we are pretty close, by day and night.

However I came across this that listed us as zone 11 - Huh ????

http://myfolia.com/zones/11

Any explanations?
Thanks in Advance.
Khaimraj

There were changes made in the official 2012 USDA map. There are now 13 zones. Zone 10b and everything higher are frost free. Of course Trinidad is not on our map, but Puerto Rico appears to be much warmer than Hawaii.
Iris

but Puerto Rico appears to be much warmer than Hawaii.

Partly, at least, because:

Hawaii is in the deep, open ocean; tradewinds are cool from sweeping over thousands of miles of open water.

Puerto Rico is in the (relatively) shallow Caribbean Sea, nearer to land and more influenced by it and by warmer, relatively shallow currents.

Miami is listed as Zone 10, but you would have to track the average minimum temperature for 15 years to compare them. I wouldn't doubt that Trinidad is in Zone 11 or warmer.
Iris