What temperature can chicks be outside w/out heat lamp?

[countrybound]

I have 4 speckled sussex and 1 blue cochin. They will be 4 weeks on Sunday. 2 are mostly feathered and other 3 are about halfway there. In Florida now, the temps are 90/80 during the day and 65/58 at night. Is this too cold at night for them to go outside w/out heat lamp?

 

[gritsar]

Give them about another week, then they should be fine in a draft free, predator proof coop. If you still have them under a heat lamp now would be the time to wean them off of it. You'll run into trouble if they are used to a brooder warmed by a heat lamp and you suddenly stick them out in a coop with no heat.