ᐅ Unfinished Baseboard in Winter – Can It Cause Damage and What Should Be Done Now?

Hello,
unfortunately, my contractor has still not managed to prime and paint the masonry in the lower area.
I’m now wondering if this area could be damaged during winter?

At what temperature is it still possible to prime and paint?
Is it still reasonable to do it now?

Or should I take other measures to protect the base of the wall?
Thanks for your help!