If you havn't surfed a winter before I'd say 4/3,
but can also depend on the length of session 1 to 1 half hours might get away with 3/2,
2 to 3 hours you get colder the longer in the water so may need 4/3,
also I surf alot at Dawn so wouldn't use anything less than 4/3 for me during Vicco Winter

.