Is 42 degrees night temp to cold?

If they are sheltered from wind/rain which can have a really big chilling effect and If they are large fowl birds and can all get under that brooder light without piling on each other, it probably be okay. I'd personally probably wait until the temps were a bit warmer and they are all feathered up. It's a big change going from 80 to 90 something degrees to 42.... Wishing you great success with this. I need to do some moving about but will wait until net week.. Nancy

 

i've got my babies in the coop (inside a hoop house) since 3 wks. the brooder was too small for the number i had & they were starting to pick at each other. i put two heat lamps in the coop (nobody else in the coop) at a level close enough for them at that age. i've been raising the lamps incrementally. i've also turned one or both off if temps were warm enough.
mine are @ 5 wks now & i still give them some heat. they're almost completely feathered, but they just seem to love snuggling under the lamp, especially after a few minutes outside in the cold.
i've been real lucky with my bunch. they seem all healthy & i haven't lost any.
the temps have ranged from upper 30s to 80s.