What is your normal low temperature? If that temperature is within 10-20 degrees of what they have already been experiencing at night, they will probably be fine, as long as their coop is adequate.
An adequate coop for that temperature needs to have a roof, and needs to keep the wind off the chickens. They still need ventilation, so moisture and ammonia and bad smells can get out, but it needs to be arranged so the wind cannot blow directly on them.
Chicken feathers are very good at keeping them warm if they are dry (under a roof, plenty of ventilation) and out of the wind.
I'm guessing your current coop is fine, but I stated what is needed because I don't actually know what kind of coop you have for your chickens.