How soon is too soon for the great outdoors

I have six adorable chicks, about four weeks old right now. I also live in Minnesota. We have some days coming up where it’ll be 85 degrees (but still too low/cold at night for them). Would it be okay to let them run around their new coop (supervised) so they can stretch their legs a bit on those WARM days and then bring them back inside for the night? Or is that not advisable and they should wait to go out until they are FULLY able to be outside?