Just after 8 AM here and now at 16 F. Might not get much warmer despite clear skies. Supposed to snow more here later on.
I'd left wet grass clippings in black bags on the South side of the house one year. Turned into quite a mess of bacterial foam, much like mayonnaise.
I'll have to experiment if things warm up here. I can always use a lawn topper that doesn't mat down into grass-choking thatch. It might be too late to try to get a heap up to any kind of composting core temperature now. If it came to it I'm not averse to peeing in bottles for a while to get nitrogen as long as I could expect results.