Late May heat in NorCal: how might it affect the grapes and vines?

I have been seeing a couple of posts indicating high 90s to 100 degrees in Sonoma. It’s late May for crying out loud! I would imagine that high heat is atypical for this early in the season. How might a few days of high 90s affect grapes and vines, if at all, this early in the growing season?

I think most of Sonoma might be coming out of bloom (guessing) so possibly some shatter issues could be possible as vines might want to put on some growth with the heat? Cabernet might still be in bloom.

What about the effect if there is any rain this weekend ?