If you're only worried about a day or two, or for evacuating/other emergencies where backup power isn't an option, I highly highly recommend keeping 1 to 3 disposable heat packs on hand per snake. I keep a case at home for mine just in case; I've had to evacuate due to wildfires before and they were incredibly helpful as I got situated finding a place to evacuate to.

For truly large collections, this may not be as feasible of an option, but for the smaller hobbyist or pet owner, the 40 hour shipping heat packs (we carry them on the site and so this is what I've used personally) are extremely useful and great to have on hand.

-Jen