According to NOAA the current heat index here in Aggieland is 98.4 with an air temp of 91. Our monthly club meeting is tonight at our flying field, and I'm PLANNING on going out early to fly a little. I managed to go out Saturday morning when it was only about 85, heat index ~93 but it was 94 air temp at noon when I left the field. I didn't even want to know the heat index, and I was one soggy pilot.
Glen is right though, it's not too bad in the fall and winter. BTW, we're planning a fly-in for November 17, R/C & C/L. Y'all come!