-20C is feasible. Charging will take a bit longer because the heater will need to work a bit longer, but as long as the batteries can reach about freezing temperature, you're good.

Charging being a couple minutes slower a few weeks a year is a minor convenience. If you have a house with a garage, like many people in the US Midwest, I doubt it even poses a problem even on the worst days. It's more in the winter-long -35C areas that (purpose-built) combustion engines have obvious benefits.

Cold climates suffer more from cold batteries having reduced range, but with modern battery ranges the problem isn't even that extreme anymore.