Teriyaki looked absolutely soaked. But when she squatted and I petted her the feathers underneath were dry.
Dumpling, the Brahma, appears to be waterproof. I saw raindrops beaded on her feathers.
This was my flock in 42 degree rain last week:
They *could* have stayed in the coop.
They *could* have stayed under the picnic fly where it was dry.
They preferred to be out getting wet and digging up bugs.
Those are quite comfortable temperatures for fully-feathered, adult chickens. Much easier for them to deal with than the 95-105F heat you'll be getting this summer.
Make sure that they have liquid water and a dry, well-ventilated coop and they should be fine.
This is my southern-winterized...