I have a similar problem here in south Texas. Our winters tend to be mild and we'll even have "warm spells". For some species this isn't really an issue. They will breed readily and productively, business as usual.
On the other hand, I also keep Pyros. They have to be kept really cool during brumation to produce well.
So into the refrigerator they go. I know it sounds nuts, but this has worked for me like a charm. I pull out the "crisper"drawers at the bottom and slide my hibernation boxes right in, complete with a thick layer of bedding, a small water bowl and a thermometer.
They should already be relatively cool before attempting this.
If you try this make sure your snakes are well hydrated. Check on them regularly and make sure they are drinking.
Good luck,
All the best,
Perry