I havent fished for steelhead in really cold weather. Lots of days when the temps were in the low to mid teens. A few times I have had half the gravel bar stick to my waders when Ive knelt on the rocks.....

When I lived over east we used to to fish for trout in the winter. Ive fished in some really cold temps, Zero and below. You do not want to fish from a 10 foot aluminum boat when the tempature gets down below 10. Ice forms on everything and the boat gets really heavy and unstable.

Ive fished for trout through the ice a few times during some long cold snaps. Thats fun.