I agree, this month has been hotter than usual for sure!
I've had waters in the high 90's in July and August.
Here is where 20-25% water changes pay of EVERY WEEK (even 2x per week) in the summer. It helps quell high water temps and the heavier waste that fish produce this time of year. Also, good aeration in hot temps with a solid air pump is very helpful as well--as hot water gets more easily depleted of oxygen.
Koi and goldfish are surprisingly sturdy critters that can tolerate cold and hot. As long as that temp change doesn't happen quickly. They adapt to cold for long periods and heat for long periods as long as it's not crazy fluctuations.