That's a good question, and one that I've thought long and hard about over the past decade in Florida. The signs are there, only they are more subtle, for example you know its really cold out, not by snow, but by the lizards moving very slowly.
The four seasons are often replaced by the summer wet and winter dry seasons, each of which has its shades of gray.
As for temperatures, by Fargo standards we never leave fall. We do get winter like blasts, but they usually only last for a day or so.
This is a topic I will explore more as we move into winter, so stay tuned.