Spraying their outdoor enclosures down several times a day will help lower the temps around them. Also the things in this thread will work for more then just the desert tortoise. http://www.tortoiseforum.org/thread-73924.html
Bringing them into the air conditioned house may have to be your option too.
I won't be getting those 100+ temps, but wish you all and your torts an easy time through it.