Modern heat pumps are rated to about -15F. In Fort McMurray, a large-ish city in northern Alberta, the average low temperature in the coldest month (January) i

Modern heat pumps are rated to about -15F. In Fort McMurray, a large-ish city in northern Alberta, the average low temperature in the coldest month (January) is -7F. The average low temperature is below -15F about 15 days a year on average. That means you’re really using your heat pump for a huge percent of the time.