There was a rainstorm here (NYC suburbs) earlier this year around July or August that sort of burned my plants. Grass wasn't visibly affected (grass isn't sensitive to much) but some flowers were turned into hard shells.

Such things have happened in other years as well, although the damage profile hasn't been exactly the same. I thought there was a chemical in the rainwater causing it, but it could have been radioactivity. I don't have a counter.

Typically it seems to happen in good growing years. This year was fine except for that.