Is it too cold at night to move older chicks outside?

I have finally finished the rebuild on the coop, and have it as predator proof as I can make it. It's ready for my older chicks (~16 weeks old now), but I'm wondering if it's going to be too cold at night to move them on outside. They've been in a brooder in the laundry room, so they've not been exposed to colder winter temps. It probably doesn't get below 60 degrees in there. The weather forecast is for several more days of colder temps, with the lowest nighttime temp going down to 20 this week. I hesitate to run an outdoor extension cord down to the coop to put a heat lamp in there at one end, for safety factors. If I bed them down with thick straw and pine shavings, will they be able to handle the 35+ degree difference in nighttime temps, or should I hold off a little until the lows are at least in the 30s instead of the 20s? I really want them out of the laundry room, but I don't want to shock them with too much of a temperature change. It took me longer to rebuild the coop than I originally expected, as I had to make some accommodations for my little curly toed girl who can't jump up and grab onto the roost like the other two, and the winter weather was not conducive to getting out there to finish up the work that I needed to do until this last weekend. Now the coop is ready, but we're getting another cold wintery blast before spring gets here. Any thoughts would be appreciated, as I'm really having a hard time deciding what to do! Thanks in advance for your thoughts on this.

At that age they will be fine outside. (They were fine at 8 weeks.)
They also have eachother to huddle together if they want to.
But they probably won't.
They don't feel the cold like we do.
And, hopefully, you were not providing any extra heat up to now so they were able to grow their nice thick down feathers to keep warm.
Move 'em outside!

Thanks for the quick reply, AlienChick. No, I have not had extra heat on them since they were quite small, after the first several weeks of adjusting the brooder temp as recommended. I just couldn't get out to finish the rebuild on the coop except as the weather would permit over the last couple of months. We had too much rain and snow, and I couldn't run the extension out there to operate my power tools with all the rain. This last weekend was dry, so I stayed out there until midnight on Saturday and finished up. I figured they'd probably be ok, but just wasn't sure about such an extreme night time temperature change. I think I'll head out there now and start bedding it down for them, and go ahead with the move this afternoon as originally planned. Thanks for the words of advice and encouragement!

t is still getting in the 30s at night here, but I have some chicks in an outdoor brooder and they've been out there since they were 5 days old, or rather I got them from the feed store and moved them outside maybe 4 days later...3 or 4 days...so They have been outside since the 9th or 10th and all are doing awesome...the low temp under the heat lamp has been 84 and that is the lowest it has gotten even when it is only 30 degrees outside...so as long as they have a properly aimed and secured heat light in their brooder they should be totally fine.
There is no reason to actually have chicks in the house at all. If they are cold they will go under the light...if they are warm they will go away from the light.

wait wait wait...16 weeks old..they can go outside anytime. No heat needed obviously. Doesn't matter if it's 70 or 12 they will be fine. I got 7 8 week old chicks last fall that went straight outside...never once were in a brooder as they were fully feathered and they all did fine.

I have twelve 4 week old chicks outside right now, they ARE with their mother. But they're big enough now to venture out on their own a little and they do, even when its cold. They sleep in the house at night and have each other to snuggle together with, so they all stay pretty warm. I stopped putting a heat lamp on them at the end of week one. But it did snow when they were a few days old.
They're doing well and they're feathering out pretty nicely.

I'm going to say at 16 weeks, they're dang near grown and they can handle it!

Hey, thanks everyone, for all the replies. I guess I'm just an old worried mother hen! I did get them moved outside late this afternoon and they seemed to have fun exploring their new space. Originally, I planned to move them out around New Years, but I didn't get the repair work finished due to bad weather, and they didn't seem to be feathered out completely at that time anyway. So they were stuck inside for a lot longer than I had originally expected. But that was ok, because I wasn't going to put them out until it was safe for them, as in totally secured against predators. These girls did seem to grow slower than the group I had last spring, which I got at 6 weeks old. Those went straight outside, and seemed to grow as fast as weeds with the warm spring weather. Hopefully these will catch up soon to where they should be at this age, now that they'll be getting fresh air and sunshine. I think I built the Ft Knox of chicken coops with the rebuild, with all the doors and windows recessed and some serious hardware latches in place. At least I hope it's a Ft Knox of coops now, as I'll be ****** if anything is going to get to this group of girls! (I never want to go through that experience again.) It's supposed to only go down to the low thirties later in the week, so if they make it through tonight and tomorrow when it dips to 18-20, they'll be ok. I'll go out and check on them before I go to bed, and I expect I'll find them all snuggled up together, without a care in the world, dreaming little chicken dreams....
Thanks again for all the comments!