If it looks like a long time problem (and assuming you've still got some hot water in your hot water tank) you could, if necessary put a plastic bottle of warm water in the tank to maintain temperature. Or pop round to me and borrow my generator and get everything going again .
The bacteria in the filter will be fine for more than an hour or two as long as you leave it in situ.
Last year we had a delivery van reverse in the road and actually knocked down a pole carrying the power lines. People came out fairly quickly to get it fixed but they were working through the night and finished in the early hours. Power must have been off for about 10 hours in total. Tank occupants didn't seem to notice! I was quite surprised there were no ill effects at all.
Mention powercuts to some of the people over at PFK and they go into spasms of fear that something bad will happen telling you the filter media is going to die off after an hour. Really you don't need to worry unless it's going to last for a long time, like days. Aslong as your room stays fairly warm you don't need to worry about temps and your filter bacteria double every 12-13 hours so even if you do have die off you won't really notice it. The biggest worry would be light for the plants not being there but if they can survive a 5 day blackout a little powercut isn't going to bother them.