We definitely had a hotter summer this year in NC than last year. I don't think my local temp broke 90F last summer more than 2 or 3 times. This year, we had a LOT more 90+ degree days. I've got a dozen Japanese Maples between landscape trees, potted patio trees, and bonsai trainees. Every one of them has shown some sign of heat stress this year except two Sharp's Pygmy trees that are in large patio pots. Those made it through the heat like champions. Second best to resist the heat have been my two Shishigashira trees. One of which is in the ground, and the other is in a nursery pot. They had very little leaf burn as well. My Arakawa in a nursery pot got burnt the worst, losing nearly all its leaves. It's putting out some new ones right now though, so I'm sure it'll be fine.
I wouldn't worry too much about your trees. Maybe just give them a little afternoon shade if anything. Cooler temps are (hopefully) just around the corner for us.
