Nectar is also highly dependant upon available moisture. It takes alot of water to make nectar and the southeast has two peaks of available rainfall during the summer bloom season, spring and fall hence our two peak flow.
Historically, the month of highest rainfall in North Carolina is July. But it seems to me that this pattern has changed in the last decade or so and now conforms to what you are saying. Did the Southeast have this dual nectar flow pattern 50 years ago?
Climate change is certainly real in my garden. Flowers that bloomed on my daughter's birthday (May 26) when she was born, now bloom 2 to 3 weeks earlier. My daughter is 25 years old.