Asterix and others, thank you!
My trainer made me wear my coat at my one and only schooling show last year. It was over 90 degrees and very humid. I did what she told me, and nearly ended up with heat stroke. I felt very “off” for a couple of days after the show.
So now I don’t care what she says. If coats are waived, mine is going to stay in the dressing room. If coats are not waived and it’s that hot, I’m not riding.