I notice the fern on the east side of my garden look similar. We have had a couple light freezes which they do not like. The protected fronds look fine. Only the ones on the outside of the bed have some brown tinge. You may want to protect your fern from frost on those really cold nights with a cover. But really, some ferns do not like cold weather in particular. It will come back bigger and older in the spring with a little help..
