We've finally had a couple of hot days, with temps in the upper 80s, after a long stretch of cooler and cloudier weather and afternoon storms. The bees have been able to get out and about, of course, but they are much more active when it's nice and hot and sunny and they can work without fear of interruption.
Warmer days also mean a warmer hive. The ideal temperature in the hive is about 95 degrees, summer and winter. If it's cold out, the bees cluster together and vibrate their wing muscles to create heat to keep themselves and their brood warm. If it's hot, the foragers are out as much as possible while the house bees work on tending to the young, cleaning the hive and managing the honey and pollen stores.
And keeping the air moving. Bees position themselves throughout the hive and fan their wings to accomplish this. Good air circulation helps maintain a steady temperature and evaporates the water that is in the stored nectar. When the nectar is sufficiently "cured" and capped with wax, that's honey!
If it's really hot out, the bees will bring in extra water for evaporative cooling. And at night, when the hive is full, the bees will gather on the stoop in large numbers, a phenomenon called "bearding." Bees will beard if the hive is too crowded (a warning sign that they might swarm), but it's also just something they do when they're hot.
When I went out in the garden late last night to cut some herbs, I could hear my bees buzzing and discovered they were bearding. I took some pictures with the flash (as above), but they weren't great.
Tonight I went out with the tripod and used my headlamp to illuminate them instead. That worked better.
Click on this photo (and the flower ones above) to see it larger.
I don't worry about swarming, as I know they've still got lots of building room, and this is a pretty small beard. I figure the girls are just enjoying the balmy summer evening.