You can dress respectful and cool and confortable for church.
Okay, good. I agree. When I see women coming in with shorts and tank tops, I pray to the Lord to send me some charity, as I have the urge to yell at them.
And, really, I have not been inside many non-air-conditioned churches in my adult life. If it is truly beastly outside, I may wear a sleeveless top or dress, but some sort of jacket goes on over it after I get out of the car.
BTW, when I was a little girl in the 1950s, our church was not air-conditioned, and we little girls and our mothers were dressed up, including hats and gloves, and slips and stockings! And the men wore suits or sports coats.