IF you have a gas hot water heater, the low-tech method of adding warmth for your snake is just a jar or bottle of hot water. Best to wrap the jar in a cloth so your snake doesn't contact anything too hot.
This ^ ^ ^ is exactly how I got thru an ice storm with power off for days, & no harm came to my snakes. You're lucky that you're not dealing with freezing temperatures: I bagged my snakes in pillow cases or snake bags (individually), then put them in large ice chests, 2 or 3 per container (can also use styro-foam shipping boxes) to insulate them from cold ambient home temperatures. Opened the ice chests about every 8 or 9 hours for air exchange (ventilation) and to change the water in the jar for hot. They all did just fine- no illnesses- afterwards. I kept an eye on temperatures in the ice chests- quite balmy & I wished I could have fit in there too.
Any travel with snakes- for their safety- is also best done this way- securely bagged & then inside a "cooler"/aka ice chest/styro-foam box- so they aren't exposed to either cold or excessive heat, which can kill them even quicker than cold. I recommend anyone keeping snakes keep such ice chests on hand in the event of any emergency that requires you to evacuate- that can be fires, floods, tornadoes, etc. Here's hoping you don't need to evacuate- please stay safe.