Answers
What happens to my heat pump in a power outage?
It stops, and so does a gas furnace, because both need electricity. What to do during a Whatcom windstorm outage, what happens on restart, and how generator backup is done properly.
The short answer
It stops. So does a gas furnace, because the blower, ignition and controls all need electricity. When power returns most systems restart on their own after a built-in compressor delay. The real planning question is not heat pump versus furnace, it is whether you have any heat source that does not need the grid.
Whatcom outages are a windstorm problem, not a heat pump problem
Our outages come from fall and winter wind bringing trees down on lines, and they hit gas-heated houses just as hard, because a modern furnace will not light without power. People who assume their furnace is outage-proof are usually remembering a gravity system from decades ago. A woodstove, a propane appliance with a standing pilot, or a generator is what actually keeps a house warm here.
What to do while the power is out
Leave the thermostat alone rather than cranking it up, so the system does not try to satisfy an aggressive setpoint the instant power returns. Do not run a generator anywhere enclosed, including a garage with the door open, because that is how carbon monoxide gets into a house. And keep the outdoor unit clear if wet snow is falling, since you want it ready to run when the line crew is done.
Restart and the compressor delay
Most equipment holds off the compressor for several minutes after power is restored, protecting it from starting against high refrigerant pressure. A brief flicker can trigger that delay too, so a system that is silent for a few minutes after a blink is behaving correctly. If it is still dark on the indoor unit long after power returns, check the breaker and the outdoor disconnect before assuming a failure.
Generator backup, done the right way
Running a heat pump on a generator is possible but it is an electrical design question: starting current, load management and a transfer switch or interlock so you are never back-feeding the utility. An interlock and transfer switch is work for a licensed electrical contractor, and extension cords through a window are not a plan. Decide the generator strategy before you buy the generator, not after.
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