temps are going down to 30's over night now,I'm still bringing 6 week old chicks inside over night.When can I leave them outside all the time?
When they have ALL their feathers, they can sleep outside with proper shelter. I would wait a couple of weeks yet if it were me, but everyone has different opinions on it. My 8 week olds are still coming in at night because they aren't integrated enough to trust them in the henhouse yet.
If fully feathered including head they should be fine out in the coop. I usually leave it to 8 weeks but that is my personal preference.
You're good now. In the spring with frost nights we put chicks out at 4 weeks and then 3 weeks of age when it's warmer. I'm waiting to 5 weeks on current batch due to the unusually cold fall, yesterday was sleeting with 34F for a high. At 4 weeks they are mostly feathered but there seems to be no repreve of sunny 55F day in forecast. I'm waiting another week. Have their heat source turned off now, in unheated garage, awaiting complete feathering and bit more size. So much for a planned fall hatch. Normally we don't turn on the house heat until my Birthday 10/20. This year the heat was turned by the 10th and in past week broke 50F twice with one morning awoke to an inch of snow.