During a typical winter (Dec. 1-Feb. 28/29), one-third of the days have temperatures that stay above freezing for the entire day. (Some might be surprised to learn that there are nearly twice as many frost-free days as there are days at freezing or colder - 34 vs. 18). There have been as few as 15 of these "January thaw" days (winter of 1970) and as many as 58 (winters of 1998 and 2012).
Since 1970 there have been 29 streaks of frost-free days that lasted 10 days or longer; half of the winters have had at least one; seven had two (the most recent was the winter of 2016-17). The longest lasted 34 days during the winter of 2015-16, lasting from Dec. 1 thru Jan. 3; there was also one of 31 days in the winter of 2006-07, between Dec. 10 and Jan. 9. December 2015 also had an eighteen-day steak in which the temperature never fell below 45°, and an eight-day streak in which the temperature never fell below 50°.