I'm sorry to hear about your Burms, SCReptiles. I own one myself and I couldn't bare to think of losing him.
SerpentLust- Your snakes should be ok. I have this same problem every year because I live in the desert (New Mexico). I always do exactly what you do... (Not utilizing the heat sources)AND I am sure to include a moist, cool place for my creatures to go. You should consider doing the same for your snakes. It's easy, all you have to do is get a butter bowl (which is meticulously cleaned, of course), put some 'frog moss' or any kind of moss inside (if you don't have moss, paper towels will do the trick) and be sure to mist it a couple of times a day. This will make your animals a lot more comfortable!