Is it your girl's first year? If not and they are older, then they could be molting. They change their energy output from egg production to themselves to renew their feathers and give their egg makers a bit of a break.
My Araucanas, who I hatched in June and July this past year, started laying not too long ago, and still are laying without any supplemental light. But next wintery season they'll be molting.
If you want to supplement them with additional daylight, it would help ramp up egg production. But thankfully, the shortest day of the year is upon us, so things will start getting longer again! Spring is so close!
Edit: temperature wise, even though this is a warm winter here, clear nights get down to well below freezing, and most days are below freezing, too. Temperature is less of an issue than daily light.