Sounds like one of our summer cool fronts. It'll be five months before I have spinach and peas in the ground. My peppers are chugging along nicely, and my eggplants are going bananas.

I have my fall stuff pretty well up, except the lettuce, so it can deal with heat if there is shade. But I did have some inconvient rain. The melons were 90% to ripe and then it rained. Then rained again. This, after a whole month with no rain. Needless to say they've either split or else taste terrible. So much for Melon Salad at the restaurant this year. Maybe you could throw a sheet over your broccoli during the heat of the day, keep things a little cooler for a week?

Broccoli, I've discovered, will tolerate a lot if you keep its feet cool.

I was so very pleased with myself for getting the fall seeds in the ground on time this year, with the possibility of a decent fall crop.

ltilton, maybe you can setup some shade for some of your plants.

WEll, weather is crazy. Here at PNW, almost zone 8, our highs are in low 70s and going down to 60s soon. A LOOOONG fall is ahead of us.

Of the fall crops, all I have is fall radish(oriental variety) and onions that I intend to use as green onions. Also experiment overwintering. I might try some garlic and shallots after the tomatoes are done.

But about your case, I don't think your fall crops will be harmed in one week. Just keep" their feet wet"'. I would cover the emerging seedlings by straw/hay ? I have seen, that is how they grow grass in the heat of summer. And keep sprinkling few times in a day.
They might grow a bit faster.