We've had onions that carry over winter in ground. They just act like new bulbs. I don't think I would plant til it warms up. You might plant them in a deep pot to hold them.

That's a good suggestion about potting them up, Marla. It's looking better going forward so I am going to plant them now.
Thanks.

Onion plants can take temperatures at least down to 15F in my experience. Temperatures here regularly go below freezing and i've never lost a plant due to the cold.
I think your only problem could be if the plants are not hardened off. The shock from the cold probably wouldn't kill them but might slow them down a bit.
-Mark

We never get near 15, Mark. These are bare root transplant so I felt like they might have less resistance to the lows, at most maybe mid 20's. We are in the normal 40's again for lows now.

Lucky you, we're supposed to have highs in the teens in the next couple of days. BRRRR!