Boo...

It's raining, it's pouring, the public hive inspections are canceled. 

You get the idea. No bees in the rain. Individual bees have less thermal mass than a raindrop. When a worker gets caught in the rain outside the hive, she will do her best to take shelter. If she gets wet, it is likely that she will lose so much heat that her wing muscles will cease to function. Without those muscles, she can't warm herself and she will die. 

I think there is a Death Cab For Cutie song along those lines....