This boots are rated for negative 40 degrees and I believe. I have worn them several times times on snowy days in Utah and my feet were toasty. The liner does a great job of wicking away sweat leaving your feet dry.
I gave this boot 4/5 of stars because it is a little difficult to take on and off.
I am normally a size 9.5 and I ordered the 9.5 and it fits great.
Once you go Sorel youll never go back...