Hope springs eternal! A light frost shouldn't do much at all. It's the heavy sustained freeze that will end your dahlia season. We too have felt the early morning chill, but no where near 0/32. I was in 3 layers yesterday a.m. til the sun came out.
If you heat up during the day, you should have every chance to see your flowers in full bloom.

If it were me and I thought it was going to frost, I would covering my dahlia's at night. I would be checking that weather forecast every night like a mad woman, if the forecast predicted a heavy frost....well I would be running around the yard with sheets in hand. Sometimes you have to do what ya gotta do to save those "babies".

Frost already, you have my greatest sympathy. Good Luck