I'm in Colorado, it's 45 degrees, wet, yucky and I am very glad my gelding is inside, dry and warm. I spent all Summer trying to get him to gain weight and now that he is gaining, the last thing I want is him shivering it all back off.
He's got a fabulous collection of blankets but he's downright convinced that the tail flaps on them are out to get him. Blanketing him results in a horse galloping around all day long if the slightest lil breeze should ruffle his tail flap. So then not only is he not eating to maintain his weight, he's running it all off.
None of the horses in he barn want to go out in this muck, especially when the alternative is a warm, dry, hay-filled stall right next to all their buddies. Plus I'll go mid-day, clean stalls, give them all attention and more hay.