Of course, in colder months it is a good idea to have either a camp stove or barbecue that can be used to heat water and a Hot Water Bottle that can be filled and placed into an enclosure to help warm the air. Others have used heat packs to help with raising temps. Both methods must be done with care not to burn the animal of course.
The other option that I have heard for temporary solution of a few days is to simply black out (using a blanket or towels) the enclosure and allow the animal to just ride out the time in the dark. They will be inactive and can be that way for days at a time with no harm. My advice here is to unplug everything just in case power comes back on. You don't need to have a fire on top of everything else going on.
I'm just looking for advice on this, but wouldn't it be bad to keep a chameleon in the dark for several days? This would at least make me nervous beyond belief. I imagine it would confuse the heck out of the chameleon too.