if they are in pots bring them in for the winter if you can. If they are not in posts, at that size I would try to pot them as I was told that smaller palms should be brought in each winter until they are mature and strong enough to cope with cold.

We have a large canary palm, and we wrap up the leaves with string (pull them in) and then wrap a large garden fleece around it.. You need to protect them from the frost. If the centre dies, you cant' revive them..