4 weeks of winter is nothing. lol If you look at some of (but not all) of the winters between approximately 1955 and 1985, winter would start early November and last through until early April.
On a sidenote, it's interesting how some of the warmest winters on record are still from 90 years ago. For example, downtown Toronto's warmest Januarys are 1) 1932 and 2) 1931, with records going back to 1840. Even January 1913 was warmer than most of the Januarys of the past 30 years...and this followed one of the coldest Januarys on record (1912).