There is no doubt that hot weather affects trout so does sunlight and high winds.Rain and cooler temperatures are not so bad although fish sense changes in atmospheric pressure and it can put them off the take.
It's hard to tell you how some strange fishery will fish coupled with weather changes. You have to read the signs on the day and fish accordingly.
You have to know what level the fish are at by experimentation and decide on your own strategy. If you name the fishery someone on the Forum may have fished it recently and give you better advice than me.
BK