You don't need to do anything. Those are very close to ideal chicken temperatures -- chickens suffer from heat but easily tolerate cold down to 0F and possibly below.
ABSOLUTELY NO HEAT!
A 50-60F day is a chicken's idea of heaven and nights that rarely frost are perfectly comfortable to them.
All chickens need for winter is a dry, well-ventilated place that's out of the wind. Their feathers keep them warm and comfortable. It's the heat that distresses them.
This thread might help reassure you: https://www.backyardchickens.com/threads/open-air-coop-in-the-snow.1508695/
Should I add a heat lamp or is nothing necessary?
ABSOLUTELY NO HEAT!
A 50-60F day is a chicken's idea of heaven and nights that rarely frost are perfectly comfortable to them.
All chickens need for winter is a dry, well-ventilated place that's out of the wind. Their feathers keep them warm and comfortable. It's the heat that distresses them.
This thread might help reassure you: https://www.backyardchickens.com/threads/open-air-coop-in-the-snow.1508695/