heat in the coop

Hi there - I'm thinking ahead to our Canadian winters. I'm near the great lakes area so we get a lot of damp cold reaching -20 C sometimes and even lower with the wind chill. I was thinking of either adding a heated water bowl or one of the heated pads from amazon like this one...

I'm at the NJ shore with unpredictable January weather. It's my first winter with chickens. My gut says stay natural, they'll be fine in the cold... until now. AT the moment, it's a humid 49* F outside (late morning)... But the Gov declared a State of Emergency, because of the winter...