I have noticed my nectar flow has slackened off around my place. The way I know without even looking at my hives, is bee behavior.
The bees were coming in my garage smelling the beeswax on the frames with new foundation. The bees are looking for nectar.
I had a frame feeder sitting by a nuc box. It had a little syrup in the bottom of the feeder. Bees were flying into the feeder getting the syrup. This behavior has been subtle. Just a few bees hitting the syrup. There is a nectar flow going on, but it has diminished and bees are searching for new sources of nectar.
When the bees discover a nectar source, foragers come back and waggle dance on the combs inside the hive. This dance tells the bees the direction, distance from the hive and intensity of the flow.
Being that it is a nearly empty feeder, the nectar available was small and not too intense. That is why only a few bees were there. There must not have been much excitement in the hive for the feeder syrup.
If it was late August I would have 10,000 bees on the feeder in a half an hour.
Weather change: The warm temperatures that are coming later in the week should get the nectar going again.
White Sweet Clover is still missing in action. Basswoods should be blooming in a week or so. At least that is when they should be blooming.