That's perfect for getting them acclimated!
Do they even sleep under the light? Before I got the brooder plate I'd find mine on the other end of the brooder once their feathers grew -- they actually avoided the heat lamp.
If they are fully-feathered, acclimated to the outdoors, dry, and out of the wind they should be fine.
Some people provide a huddle box for them to snuggled together in, but even though I give them one mine have always refused to use them.
Are they acclimated to the outside or are they kept...