Many people in the Pacific Northwest do not think to go to the beach during the winter. I love the beach anytime of year.
I find that a pair of thick wool socks with rubber boots and a good raincoat can keep one fairly dry. If it is cold out, simply add some long underwear, a warm hat that fits snugly in the wind, and take a pair of gloves along. Keeping your core warm and your body dry is the key to a good winter walk on the beach.