Sometimes, yeah. Colorado has gotten a couple of oddballs over the last couple of years. The River Jewelwings were odd enough, although they do have a few records from Wyoming. Slaty and Bar-winged Skimmers, though? Waaay out of their usual haunts.
Generally speaking, they can get going once the air temperature hits around 65F, but if you get a night with a relatively high dewpoint, they tend to stay put until it burns off. Meadowhawks and some Skimmers also tend to stay stationary longer than Darners, so even if it doesn’t really cool off, it might still be worth your while.