Dear Dr. R.V. Shrink:
We have decided to spend our second winter on the road in Florida. We spent our first winter in Arizona and froze to death. We thought Arizona was like Hawaii but found out that is not the case. Now we are cold in Northern Florida and I want to go to Mexico next year. My husband refuses to take our RV into Mexico, so where the heck can I go for the winter and be warm? I might just as well stay home next to the wood stove. --Cast member from the movie "Frozen"
If you don't want to go to Mexico and keep heading south until you find warm weather, do it in Florida. It's a very long state with lots of micro climes. The farther you head south the better your chances of finding warmer weather.
You are right, the desert gives up its warmth at night and you will experience many more cold nights and mornings in the West. The days are typically warm and sunny, but you have your windows opened at night much less than if you were in a climate like Southern Florida.
How about meeting halfway? Try Brownsville, Texas.
You may not find the utopia of weather in the south during the first couple months of the year, but it still beats chopping firewood. You could be like the cast member Elsa and just, "Let it go." --Keep Smilin', Richard Mallery a.k.a. Dr. R.V. Shrink