1991-2020 Degrees Fahrenheit 1 23.9 18.9 5.0 63 9 1977 2006 2016 2012 top-third 2 22.5 21.6 0.9 44 28 1977 2002 2014 2016 normal 1981,2005 3 29.7 26.6 3.1 65 7 1977 2002 2015 2016 top-tenth 4 36.0 32.4 3.6 68 4 1977 2002 2015 2016 top-tenth 5 42.0 38.4 3.6 69 3 1977 2016 2015 2016 top-tenth 6 47.1 43.7 3.4 68 3 1977 2002 2015 2016 top-tenth 7 50.6 47.7 2.9 69 2 1977 2002 2016 2002 top-tenth 8 53.0 50.3 2.7 70 1 1977 2002,2017 2016 2002 highest 2002 9 53.7 51.2 2.5 69 2 1977 2002 2016 2002 top-tenth 10 53.1 50.8 2.3 69 2 1977 2002 2016 2016 top-tenth 2016 11 52.0 49.4 2.6 69 2 1977 2013 2016 2013 top-tenth 12 49.9 47.2 2.7 69 2 1952 2013 2016 2013 top-tenth 18 49.0 46.0 3.0 68 1 1979 2017 2016 2017 highest 24 49.0 47.2 1.8 65 4 2015 2013 2016 2013 top-tenth 36 47.5 47.2 0.3 50 17 1963,1979 2013,2018 2016 2014 top-third 1990,2004 48 46.7 47.2 -0.5 35 30 1980 2002 2012 2016 normal 1993,1995,2012 60 47.4 47.2 0.2 49 14 1963,1980 2003 2016 2013 top-third 1957,2009,2013