1991-2020 Degrees Fahrenheit 1 45.8 46.8 -1.0 66 60 1907 2010 1997 1999 normal 2 44.2 41.3 2.9 116 8 1926 2012 1999 1991 top-tenth 1973,1991,2004 3 40.7 36.8 3.9 121 3 1904 2012 1999 1998 top-tenth 4 37.2 34.2 3.0 116 6 1904 2012 1999 1998 top-tenth 5 36.4 33.7 2.7 115 7 1904 2012 1999 1998 top-tenth 6 37.8 34.9 2.9 117 5 1904 2012 1999 2000 top-tenth 7 39.6 37.3 2.3 116 6 1904 2012 1999 1921 top-tenth 8 42.5 40.6 1.9 114 8 1904 2012 1999 1932 top-tenth 9 45.4 43.9 1.5 113 9 1904 2012 1998 1999 top-tenth 10 48.4 46.7 1.7 116 6 1904 2012 1999 1999 top-tenth 1999 11 50.2 48.6 1.6 117 5 1904,1918 2012 1999 1932 top-tenth 1932 12 51.1 49.4 1.7 116 5 1918 2012 1999 1999 top-tenth 1999 18 46.3 44.5 1.8 112 4 1918 2017 1998 1999 top-tenth 24 51.1 49.4 1.7 112 3 1918 2017 1999 2000 top-tenth 2012 36 50.5 49.3 1.2 108 3 1918 2013 1999 2000 top-tenth 2008,2018 48 49.7 49.4 0.3 94 13 1918,1919 2002,2013 1999 2000 top-third 2018 60 49.2 49.3 -0.1 82 22 1920 2002 1999 1992 top-third 1992