I've talked to the County Agent about this several times & he says it's ok to aerate any time of the year except during frost. I think that would only be common sense not during the frost.
If you have a County Agent, they are very helpful & can help you quite a bit in most cases. I used mine a lot & got a lot of very good advice! They have a great deal of know how, experience & all kinds of resources to help you & your company be successful! BTW that's their job!
Sorry for the Short Post, I'll try to do better next time!