During a power outage it's always a good thing to have a backup source of heat to heat your home because when the power goes out your furnace with the blower will not work.
A natural gas wall heater that is vented is a good idea or even those natural gas vent free heaters are good for use in emergencies and they don't require electricity to run.
A wood stove is another option or a coal stove that doesn't require power.
If you have no other form of emergency heat then you need to layer in blankets and bundle up really good to keep in your body heat.
If you have to sleep in the cold in your house then layer on lots of blankets and wear a coat to bed as well.
Cover your whole body and entire head with the blankets because the breath you're breathing will be warm and will warm you up under the covers nicely.
I've done that before and I survived a freezing cold house for 2 weeks until the power got restored after an ice storm.
A portable propane buddy heater can also keep you warm or even a torpedo heater but be aware of carbon monoxide poisoning.
When a power outage may occur such as an oncoming ice storm be sure to turn your thermostat up so the furnace will run longer and heat your home to a warmer temperature.
This will help keep your house warm for a little longer after the power goes out.