Not sure where you are located, but I had some hatch in late July one year... I left them running loose with mom. October came in with 90 degree weather on the 1st, by the 5th temps dropped below freezing and we had a major blizzard. They got separated from their mom, and it took about 3 days but they did all straggle in from where they were hiding and we didn't lose even one. Then they went through a North Dakota winter in an unheated building with 24/7 access to an outdoor run.
As long as they have somewhere with roosts to get out of the wind and weather, they should do fine.