1991-2020 Degrees Fahrenheit 1 33.2 27.7 5.5 121 6 1904 1998 1975 1976 top-tenth 2 28.9 27.2 1.7 108 17 1912 1998 1975 1944 top-third 1944,2016 3 29.7 28.8 0.9 103 22 1904 2002 1975 1954 top-third 4 34.0 31.8 2.2 114 11 1904 2002 1975 1932 top-tenth 5 38.0 35.8 2.2 116 9 1918 1932 1975 1932 top-tenth 1999 6 41.3 40.4 0.9 108 17 1918 1932 1975 1954 top-third 7 45.6 44.8 0.8 110 15 1918 1932,2017 1975 1954 top-third 8 48.9 48.2 0.7 110 15 1918 1932 1975 1954 top-third 2020,2021 9 51.1 50.3 0.8 111 14 1918 1932 1975 1954 top-third 1992 10 52.1 51.0 1.1 110 14 1918 2017 1975 1954 top-third 11 51.2 50.7 0.5 107 16 1918 2017 1975 1954 top-third 12 49.6 49.4 0.2 99 22 1918 2017 1975 1954 top-third 18 46.3 46.4 -0.1 95 24 1918 2017 1975 1954 top-third 1950,1989,1996 24 48.9 49.4 -0.5 84 32 1918 2013 1975 1956 top-third 1950,1956,1984,1990,1996 36 49.0 49.4 -0.4 83 28 1918 2013 1975 1956 top-third 1999,2010,2011 48 48.6 49.4 -0.8 71 36 1919,1927 2002,2013 1975 1957 normal 1987 60 48.5 49.4 -0.9 65 39 1920 2002 1975 1958 normal