I’m in Las Vegas and we ride at 5 or 6 am to avoid the extreme heat. That way we are done before it gets to the 90s. If it cools down there late at night, that’s another option. At my old barn, we had lights so we rode at 8 or 9 pm if it had cooled down enough. I also agree with all of the other hot weather tips mentioned, but as far as not riding, we just ride really really early or late to avoid it.