It depends where you live in Florida. The temps in the northern part of the state can get pretty nippy compared to the southern part of the state. Also, some Florida folks may have a lot of trees that lose their leaves so therefore there’d be no tree cover. Other areas of the state have palm trees.
*** We just moved here last December. There were some leaves left on the trees but it appears the squirrels make their nests in the spanish moss. There were some cold nights (we live in Dunnellon, near the Ocala line). I believe we covered our pool filter and well twice because the overnight temp approached freezing but, from what I'm told, that was rare.
If she is not pacing and anxious to be free then I’d err on the side of letting her be older when released. I think older squirrels are better prepared.