Several of my roses are doing that too. Too much rain and then BOOM! Instant July temps. The air is hot and humid, but the soil is dry. Haven't had one drop of rain since our 14 inches in two days time. Some of my tomatoes are doing that too. It got too hot too fast.
Tomorrow I am going to mix up some Miracle Grow and give them a dose like tonic. Miracle Grow promotes leaf growth in plants. Them I am going to pile on some hay around their "feet" and see if that helps. You can bet that soil is hot.

When I water them, the next day that moisture turns to steam and that rises up and cooks the leaves. If plants think there is a threat of drought, or get stressed out in some other way, they will drop their leaves to conserve their energy to stay alive. Trees do that too.

Darned goofy weather!
~Annie