My TB cross gelding is an absolute princess when it comes to the weather. If he's out and its too chilly or too wet for his liking, then he will stand at the gate and paw, and/or shiver, until you either bring him in or put a blanket on him. So, I do blanket. Generally, a sheet for rain and temps around 40-50F. A mid weight with a neck cover for dry and temps to about freezing, for raining and temps to about freezing, mid weight with a fleece. Once it goes below freezing he gets his heavyweight with a neck cover, and if its raining/sleeting/snowing, he gets a fleece on underneath.
He's such a diva.
But he's always clean :)