when can they start living out full time?

[spish]

i have 9 chicks here that are nearly 2 months old, fully feathered now. i put them out in the morning and bring them in at night but would like to know will they survive outside all night? we've just built them a chicken house, and im going to put it out in the field next to the other chicken house, but with a large fence around so the chicks can go out and in as they please, but the bigger chickens cant get them.
my only concern is the temp. its really 'changable' here at the moment. two days ago it was 15 degrees at night, now last night and tonight its back to 0 and 2 degrees, yet tomorrow they give 5-8 degrees!
would such a swing in temps be bad for the chicks or are they big enough now to go out? when kept inside our house they are stuck in a cage in the back kitchen that is 100cmx60 far too small for them now. their new chicken house is far better for them!

 

[Ridgerunner]

At 8 weeks and fully feathered, they should be fine outside, even with it getting down to freezing aoccasionally. The coop will probably be warmer than outside anyway with their body heat. They will probably just hudddle on the floor to keep each other warm instead of roosting at that age. Very few broody hens are still providing heat and shelter at night to their chicks when the chicks are that age. Chicks that age are too big for many to fit under the hen anyway.

I don't know what your coop looks like, but I imagine it is a lot bigger than the brooder you have them in now. If you can, I'd suggest locking them in the coop for a week or so before you allow them to roam in the run even during the day time. This will teach them to sleep in the coop where it is more sheltered from wind and rain instead of sleeping the run.

Good luck!!!