>why would anyone open up all their colonies in February in Pennsylvania? In NY we usually don't recommend poking into them until April. This year, being so warm (9 degrees above normal for Feb) I would probably move that to March, but not Feb

Well, I suppose it is a matter of experience and of opinion -- and probably a question of how the bees are wrapped or packed, or not.

Up here, commercial beekeepers open hives any day of the year that it is above freezing and not breezy if they have the need to, or simply out of curiosity.  Some of my test hives have been opened at least 20 time since October and they look OK.   

Opened for a quick look, yes.  Frames pulled, no.  Pulling frames is done on occasion when justified, but very judiciously, and when they is no wind at all.  They are replaced within seconds.

Cursory checks have to be done in Jan and Feb to estimate the state of the hives and likely winter loss in order to plan for feeding and to order replacements.  Most beekeepers here are feeding protein, where indicated, by mid-March.  Many will move side frames around or provide syrup if there is risk of starvation.  Disturbing frames with bees on them is a different matter.

Some hives are wrapped in a manner that makes all this difficult, but most these days wrap in a manner that allows quick access.  

Unwrapped hives often shouldn't be opened as casually since opening them would break the seal and a 1/16" crack under a lid adds up to a 4 square inch hole in total area (1/16" x 60"), and allows wind to blow right through the brood area afterwards.  Some who don't wrap  have a lid system that reseals, however, as do I.  (I don't wrap.  I use EPS boxes and pillows under lids).

Just lifting a lid does not seem to have any effect on winter survival, but prolonged exposure can be harmful.  we've had lids blow off hives and found them open for a week or more in late fall, before wrapping and found the hives survived just fine.

In winter, almost broodless, clustered colonies are actually less vulnerable to harm from an opened lid than they are later, in spring, when fewer, older bees are trying to cover larger amounts of brood.  

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