Basically, they all did.  It seems as if they were responding to a different triger.  Such as a secondary  vernalization preferntial signal. That is a certain amount of time as a  mature plant. Or something similar.

Very puzzling.

Autumn Embers, a fall cylic SDB,  blooms late in fall, normally around end of Sept. This year reblomed on Aug 10th. And not just one stalk, so not one of those occasional biological misfires. Never seen this before on this cultivar. It is my into  and  has been blooming here since 1989. Until this year has always rebloomed late  Sept or early Oct. Or  frozen out before rebloom. Never earlier, until this year.

As this is all a one time phenomenon for me, I have no idea what to make of it

But as I mentioned, very early bloom seson (about 2-3 weeks earlier then normal) and  very warm summer with no extreme hot spells, and a good steady rainfall without any long droughts . An ideal  and very rare summer weather.

Chuck Chapman