What kind of herbs? If anything other than very cold sensitive basil, they should be fine outside - mine are outside year round and they easily withstand cold and even below freezing temps. I harvest them year round as well :-)

You just need to gradually acclimate them to outdoors as an all-at-once shift can shock them. Take them out for a few hours the first day, gradually increasing the time each day until they stay out overnight......should just take a week or so.