@1980Mooney, here in Sweet Home at 1030 the temp was 81° with 80% humidity for a "feels like" temperature of 89°.
Right now at 1500, the temp is only 89° because it's pretty cloudy with thunderstorms moving around, and humidity is 60% for a "feels like" temp of 98°.
Summer is almost here! Just as "hot summer weather" varies around the country, so does "staying cool." I saw an Irish newspaper once with 4" tall headlines for a heatwave that was killing people--converting from Celsius, it was 81° . . .
So, @Beaker, take the advice here and use whatever you need until you are comfortable. I departed Indianapolis one hot summer evening, ATIS was calling 96° but my OAT on the runway was 110+; when I leveled off at 9500 msl for my short 1-hour-plus flight (just to stop sweating), it was a nice 59°, roof vent was open, vent below the throttle was open, Vent knob on the panel was fully open and both knee vents were wide open. After about 15 minutes, I was starting to feel pretty good. Descending to land, I got pretty warm again, but had a very short taxi (less than 1/2 mile).
And as always, fly safe!
P.S.--having lived in both climates, I'll take 100° anyway rather than 0°!!