I'll start by saying that I have nothing to complain about compared to you folks in states where SNOW can be a real problem at fleas and life in general, but that said, let me tell you about central California winters.
In my area the problem in Dec, Jan, Feb is RAIN and sometimes COLD. Nothing stops a crowd from coming out like a good rain or a continuing drizzle. Even with canopies, that wet stuff just puts a damper on selling. Factor in some wind driving rain sideways and you get a lot of people wanting spring to arrive.
The last 10 days or so it has been 30 or 32 at 5 and 6 a.m. and then by noon or 1 pm its 55 to 60 degrees. That may SEEM desirable, but it still puts a damper on things. I wear 4 layers on my chest and 2 layers on my legs and feet and then have to start peeling those layers off....granted, it's better than not going at all, or shoveling off snow, but still a pain.
One thing that sells well in the winter here are propane heaters on top of 20 gallon tanks. I have one that size and one of the $100 "Buddy" heaters that uses the small green propane bottles. Both were sitting outside my van and half a dozen people wanted to buy them. I use one or the other depending on how long lasting the cold morning is. The big one really puts out the heat....I use them both INSIDE the van and sit in the open sliding door....makes quite a difference in making it through the morn.
So, in my area we are always looking for the month of MARCH to roll around when we can fight the winds...and sell KITES !