At 8 weeks old they can withstand anything. As long as they have water. The tendency, from experience is to over feed them to make up for the cold. DO NOT DO THIS. They are little heat generators.
Mine live outside in a "box" with a tractor attached, I free range them during the day when I am home. They cuddle in the extreme cold and do fine. I have not even had one lose a comb. BTW your cold is a nice spring day for me.