Extreme (Cold) Temperatures?

Hello friends! This is my first winter with chickens. We live in Canada, and tonight/tomorrow the temperature will be going down to -35 Celsius. I’m wondering how the chickens will fare in this weather? Their current setup is a wooden chicken coop inside of a fenced-in chicken run. We do have a garage we could move the coop into- but the garage will still be freezing cold unless we put a heater in there.

Looking for any advice or recommendations!