I spent the first 40 years of my career working outdoors building houses every winter and was pretty comfortable down into the teens unless the wind was blowing or the footing got too icy. I spent one winter early on in Vermont and that was the only one I took off. Now, in our later years, we go up to our place in the woods there, and I'm fine with our wood-heat-only cabin but there are times you really can't stay outside and do anything for very long unless you're totally bundled up. Still, I'd rather that than the last two days working at my son's in 95 degree heat and high humidity.