This was in the newsletter from Brushy Mountain Bee Farm I just received - so, so true.
The spring flow has been terrible this year. Any reserves are quickly consumed when the bees are house bound by all the rain and cool weather. Once this weather pattern breaks watch for swarms. They are crowded in a hive by the weather with nothing to do, so "hey lets make swarm cells". O.K., this is an over-simplification and imposes human traits/characters on the bees, but you get the point. This time of year there a spike in swarming activity after several days of rain.