Chickens Arctic Conditions Prolonged Period

[Hokum Coco]

It's really cold here in Ontario right now. We have snow, so I can't free range the chickens as usual. I guess I should have a protected run, but I don't. I hate to keep the chickens shut in the coop. Any suggestions?

Temperature:
Temperature:
-7.2°F
Dewpoint:
-22.2°F
Humidity:
48%
Wind:
W 13 gust 19 mph
Wind Chill:
-27

-21.8°C
Dewpoint:
-30.1°C
Humidity:
48%
Wind:
W 21 gust 31 km/h
Wind Chill:
-33

I feed extra corn during this cold snap above are the temperatures today In New Brunswick were I live in both Celsius and Fahrenheit.
They also enjoy a head of lettuce or celery anything that is going limp in the drawer I call the rotter in our fridge. I do not have an enclosed run either but I do open the pop door to let them venture out (they usually do not or if they do it is only a few seconds).