Good thread. It's always a concern. In a power outage in weather conditions such as these, when it's colder than a witch's teet, all you need to be concerned about it keeping the water warm. CO2, lights, filters, and scuba divers with bubbling treasure chests are all distant seconds. The fish will go into a pseudo-dormant state while the lights are out, decreasing their activity significantly so feedings aren't necessary, even for several days. They'll be fine. Since you won't be adding so much food and creating waste, filtration can be put on hold until you regain power. Battery powered airstones are inexpensive and will get the job done for aeration. You can also aggitate the surface with your hand or a plastic cup every so often to facilitate gas exchange. It doesn't have to be elaborate and you don't have to blow into a straw for hours on end.
Check out the battery backup units they have for computers. You might be able to find something that will run your heaters.