I'm scratching my head over this..Here in Southwest FL the totality was supposedly over 70%..Went outside to typical brilliant sunshine at 2:45,took a pix of the sun and came back out at 2:53 (Our max time according to the news) no change at all...
As you said Archie some NJ storms will black out the sun better,but down here even more so in summer.Streetlights turn on.