I live in San Francisco average temp is in the 60s, when I ride in hot weather I suffer. I grew up in Arizona until I was 16 where temps in the summer were well over 100 and remember playing golf and baseball in that weather. Now anything over the high 70's I suffer. Courious about this I found our national weather service has great advice on hot weather http://www.nws.noaa.gov/om/heat/index.shtml.