Not as warm as expected.
I tend to have cold fingers and toes when boarding, so I ordered these 1 size larger than usual to leave room for heat packs. I wear a Medium in Mechanix gloves, so I ordered a Large in these mittens and put a heat pack in each hand in between the fleece liner and the outer shell. The temperature was in the single digits with the wind chill dropping below zero at times.
These mittens were toasty on sunny days with the temp in the 20's without heat packs.