eight 3 week old chicks, can they handle 69 Degrees at night?

I would say it depends on their feathering--but ideally they should be 5-6 weeks before making their final move. If you are keeping them cooped up in a shelter with no drafts you might be able to sneak them out sooner...don't rush it--they will be outside for the duration once they get there...and the risks of a premature chill will ruin all of your hard work...Good luck