I have the perfect solution as this happened to me once. Then I bought a generator. Anyway this is what you do. Always have a hang on the back filter for back up if you don't use one or get inventive with your canister. I'm going to explain this with the idea that a hang on the back filter is being used.
1. take the lid off.
2. find a clean hose such as a python hose about 1.5 inch in diameter give or take a little.
3. put one end in the tank
4. then just syphon water into the filter (It will run on its own with no electricity)
As for the heat this can be tricky.
1. have the syphon hose swing off to the side of the tank
2. place some boxes or books (or what ever you have) next to tank under the hose
3. put a candle on the books and light it
you may have adjust the height of the books for proper temp (do not melt the hose)
here is a small pic I drew up (I'm not an artist

) that will give you an idea of what I'm talking about. Feel free to alter in any way to suit your needs.