I'd make plans to take him with you if at all possible.
Buy a small-ish tub with a lid...just big enough for him to lay curled up in one-half of the tub. It could be bigger, but the smaller it is, the easier it will be to travel with.
-- If you can find one...a human heating pad that does NOT have an automatic shut-off will work for a heat source.
-- If you can't find one, then get a UTH from the pet store that will fit under about half the tub.
-- A dimmer switch for table lamps from the hardware store. (It's like an extension cord with a dimmer switch on it)
-- An indoor/outdoor digital thermometer from the hardware store or walmart.
--A small water dish.
-- Something to make sure the tub lid stays secure...clamps, bungee cords, heavy book, etc.
While away from home, your goal is just to keep the overall temp of the snake's enclosure around 80-85 degrees. Don't worry about warm and cool zones.
For those who have multiple snakes...you can get a bigger tub...one big enough to allow each of them to lay on the floor of the tub curled up, without being on top of each other. Place each snake in individual bags (inside-out pillow cases work fine) and tie securely. Lay them out in the tub...some extra towels on top to fill in the empty spaces so they don't slide around during travel. If you place a heating pad on TOP of the tub, then wrap a blanket around the whole thing, you can create an ambient temp in the low 80's without making a hot spot that just one or two snakes are laying on. They can safely stay like that for 24-48 hours. If you'll be evacuated longer than that, you may have to get creative about bringing multiple small tubs to separate them so they can move around and get a drink.