10-Jack's fluffy

My dog jack is a tiny 10 lb boy that is usually not this fluffy. He looks like he's around 20 lbs now when you look at him. I try to brush him so he doesn't matte... I just don't want to get him a haircut while it's -25 outside because he'll freeze! Right now he doesn't mind being out for a bit because he's got his big coat on but he does look ridiculous with all of this hair! When I measure his hair it's as long as my index finger...I sure hope when I take him in for a haircut they don't shave him because of mattes... he doesn't look good like that!