I have 2 wk old Barred Rock chicks. Up until today it has been in the 90's, so every day my son and I have taken them outside for a little fresh air and let them peck around in the grass. Not long - just 20-30 minutes. Today and for the next few days it will be quite a bit cooler (upper 60's to lower 70's). Should I keep them in when it's this cool, or would our usual short playtime still be ok?