Most likely - something came up! either some threat at destination or route OR ... something came up! Maybe something BIG is about to DROP? ;)
Or maybe the heat was a factor?! Who knows at this point.
I used to work at a N.VA course. Those weather conditions did reap the old dudes in droves plus you always had the afternoon thunderstorms that could spring up quickly and ZOT folks. I usually golfed in either those conditions, or rain, because it thinned the herd back quite a bit.