Fern fiddlehead

My backyard ferns continue to thrive without any moisture except from sparse winter rain and despite freezing temperatures. As a frond (leaf) grows, it unrolls from the top, resembling a fiddlehead. These ferns, stimulated by recent warm temperatures and rain, are developing into a ground cover in a corner of the garden. Will the predicted freeze tonight damage them? We’ll see tomorrow. I’m not covering them to protect them, but expect to see them as green and healthy in the morning as they were this afternoon.