These are certainly warm boots - been wearing them the past couple of days during our single digit temps and I've been comfortable. Not too warm as I can leave them on indoors, walk around a store or two, without becoming "overheated". I found the wide boot in my normal size (13) to be comfortable. I don't always need a wide, so I believe these tend to run a bit narrow. Moving up one size like others suggested for this boot would have been too large for me.