They'll be fine. The critical temperature at which buried potatoes will begin to freeze is usually around 20 degrees F and even that's for potatoes that don't have mulch.

Most potatoes are likely a little deeper. My guess is that one night probably won;t freeze them.

That's a relief! I'll have harvesting help this weekend.

I probably don't have the same variety as you, but I've forgotten to dig some of mine before and they were fine in early spring. In fact, they were so much better than the ones I had in cold storage, that I've considered leaving some in the ground on purpose.

They should definitely be fine for fall early freezes.

Bellatrix