Cannabis is a hardy plant. It can usually survive mild frosts as well as mild snows. However, continuous nights like this will impare flowering. I suggest you force flower your plant so you are able to harvest. Use a large bag that is light proof so you can effectively flower your plant. It usually takes 6 weeks for a plant to finish flowering so I hope the nights warm up. By chance are you in the NW of the US?

Happy Toking :rasta: