We have had the warm spell blow in that much of the country saw. Came up to 49 today, the sun even peaked out for awhile. The last few days have been similarly mild, so the hives have had a chance to "warm up" (from sub zero temps)
I expected to see some if not most of the hives show some activity. I can hear them buzzing inside. But I checked a few times through the day and saw one solitary bee slip out and back...and a few dead in the snow that may have been new or might have just melted out in the thaw.
Wind was generally mild, sun was weak and brief.

So what is the trigger(s)? it seems like strong sun is a pretty significant component. I know I have seen them active in cooler weather with full sun