It's a little late for prep if you don't already have stuff on hand. Like chemical heat packs used for air shipping reptiles. (or similar "hand warmers") Also, ice chests/thick styro-foam chests & cloth bags for each of your snakes, with wire twist ties & rubber bands to make sure they can't escape. I went thru an ice storm in '09- no power for 4 days- & none of my 15 snakes got sick or harmed in any way- they were bagged & put in ice chests (not crowded, only a few per chest, of similar size) with jars of hot water (helps to have a gas hot water heater!) for warmth- they stayed a balmy 78-80* for about 9 hours, at which point I changed the water in the jars. BTW, find large empty jars or plastic soda bottles too.In an absolute pinch, bag your snake & put him inside your shirt- YOU can be his heat in an emergency- but that's pretty hard if you have a lot of snakes or large ones, unless you have a big "understanding" family to go along with them. And pretty challenging if the power stays off for a while, so let's hope no one hits a power pole or anything.
You might fill some bottles of water to have on hand. (It's bitterly cold where I am too.)