Into Florida: https://www.hertz.com/rentacar/renta...lorida-atlanta
Into Arizona: https://www.budget.com/budgetWeb/dea..._onewayArizona

There seems to be availability this Fall, at least from Boston to Southwest Fla. It looks like the last day for pickup is Dec. 10th, perhaps a little earlier than past years. (Dollar, Thrifty, Hertz)

Thanks for the info. I'll keep watching. My need is a bit later than the 10th. (Last week of Dec)

Based on my research, I've concluded that the rental companies must either have an easier time moving the fleet south, or they are not under as much time pressure (or both). There are a LOT more websites that talk about coming back in March/April than there are talking about going down in Nov/Dec.