When can they go outside permanently?

You can put them outside if you provide a heat lamp in the coop for night time in case they get cold. Usually they would need to stay in a brooder at night until they are feathered in... you can start putting them outside during the day for short periods at 4 weeks or so. Make sure you provide them with water and show then where it is.

 

i live in alabama and our temps are identical to yours. i moved my 4 week old chicks from the inside brooder to a large wire cage. I put the cage inside the coop so my other chickens can start getting accustomed to them. They have managed fine at night for the past week. I plan to let them out a little at a time when they are 6 weeks old. By 8 weeks, they will be out with the rest of the chickens all the time. I have a light that i turn on now when it gets below 60 degrees at night just as a precaution.

 

I have 4 chicks and a duckling that are all about 3-ish weeks. I live in Boise and the temps during the day now are getting up to anywhere from 54-74. They have a good number of feathers in already and although the duck is later in getting her feathers than the chicks she is larger, fatter and covered in a cozy layer of white fluff. As soon as the temp reaches above 50 in the morning I take them out of the brooder (in the garage) and put them out either in the run or I let them run in the yard if I am planning to be out with them. They stay out most of the day now and they don't even need the lamp anymore. I do put them back in the brooder at night still. I am waiting at least another week before putting them in the coop because it still gets chilly at night and I would rather not wire the lamp out there. What I hear from most people is that the sooner you expose them to lower temps, the hardier they become and the less suceptible they are to cold later on. Certainly I'm not going to make them freeze but they have seemed perfectly comfortable so far and I would rather not have to ever put the lamp out in the coop.

 

As soon as 3 weeks old only if the temp stays above 65. I put my 3 week olds out but turned on the heat lamp in their area when the temp dropped below 65. Remember that corners are you enemy if they get chilled. They will huddle so tightly together even at 3 weeks old they can break legs and even suffocate others if they get cold enough. A chicks everyday body temperature is 103 degrees, so that 65 feels colder to it than it does to us.