I have a strong hive that's taking long lunch breaks. The bees get active early in the morning, and keep going strong until about noon. Then things get quiet around the hive for a couple of hours. They get busy again around 2 pm. I've never noticed this behavior before; is it unusual?
I doubt that it's weather-related. I'm in Massachusetts, and it hasn't been hot (until today). There's been no bearding to speak of.
It may be that the flowers that they are visiting are only flowering or producing nectar in the morning. That would be my guess.
You're probably right cao, I seem to remember that not all flowers do the same thing at the same time. Too much competition for pollinators.