1991-2020 Degrees Fahrenheit 1 60.9 59.8 1.1 67 18 1988 2007 2018 2017 top-third 2 66.5 65.4 1.1 75 9 1940 2007 2018 2017 top-third 3 70.2 69.6 0.6 69 15 1940 2005,2007 2014 2018 top-third 1998,2020 4 73.0 72.0 1.0 75 9 1940 2016 2017 2018 top-third 5 73.0 72.3 0.7 75 9 1940 2010 2017 2018 top-third 6 71.1 70.9 0.2 68 16 1940 2010 2014 2018 top-third 1955,1995,2001 7 68.7 68.5 0.2 71 13 1940 2010 2014 2018 top-third 2013,2020 8 65.3 65.3 0.0 66 18 1940 2010 2014 2018 top-third 1955,1973,2008,2011,2013 9 62.0 62.1 -0.1 65 19 1940 2010,2012 2015 2018 top-third 1953,2004 10 59.1 59.4 -0.3 60 24 1940 2012 2015 2018 top-third 1973 11 57.4 57.6 -0.2 63 21 1940 2012 2015 2018 top-third 1973 12 56.5 56.9 -0.4 60 24 1940 2012 2015 2018 top-third 2011 18 61.7 61.6 0.1 67 16 1948 2016 2018 2017 top-third 1995 24 56.7 56.9 -0.2 63 20 1941 2017 2015 2018 top-third 2003,2005 36 57.3 56.9 0.4 73 9 1942 2012 2016 2018 top-third 2000 48 57.9 56.9 1.0 79 2 1943 2013 2018 2013 top-tenth 60 57.4 56.8 0.6 73 7 1944 2020 2018 2016 top-tenth 2002,2014,2016