As long as the cold doesn't last too long and the roots don't freeze they should be fine. You might get some wilting leaves on the young green branch tips. Even if the roots get too cold they will come back, but your season is so short you need to keep those roots warm.

Please send some rain this way! We are in a drought also. A few minutes ago we heard thunder and saw the clouds coming so we put out the rain barrels. Now it's sunny again and we only got a few drops. Should have known setting up for rain would make it go away.