We have a 3-season sunroom but since it sits on the west-end of the house, it gets down-right warm in there when the sun hits that glass for a few hours. We use it year-round. It might as well be heated.
I use one of those long-handled roof rakes to take the snow off. Ditto for the decks and other structures that have weight on them from the snow. One gallon of water weighs [~18lbs]
~ 8 lbs - taking that weight off - melts or not - will prolong the life of the structure.
And it's a good way to burn off all those Christmas cookies you ate!