1991-2020 Degrees Fahrenheit 1 30.5 27.3 3.2 113 14 1904 1998 1991 1987 top-third 2 30.0 26.7 3.3 114 11 1912 2023 1991 1990 top-tenth 3 30.4 28.3 2.1 113 12 1904 2002 1991 1983 top-tenth 1919 4 32.0 31.3 0.7 102 23 1904 2002 1990 1991 top-third 5 36.1 35.3 0.8 103 22 1918 1932 1991 1991 top-third 1991,2020,2021 6 40.3 39.9 0.4 99 26 1918 1932 1990 1991 top-third 1919,1964 7 44.7 44.3 0.4 105 20 1918 2017 1991 1983 top-third 1931 8 48.1 47.6 0.5 106 19 1918 2017 1991 1983 top-third 2011 9 50.5 49.8 0.7 110 15 1918 2017 1991 1976 top-third 1976 10 51.8 50.6 1.2 112 12 1918 2023 1991 1932 top-tenth 11 51.7 50.2 1.5 113 10 1918 2017,2023 1991 1932 top-tenth 1932 12 50.5 48.9 1.6 114 7 1918 2013,2017 1991 1992 top-tenth 2002 18 47.2 45.9 1.3 111 8 1918 2017 1991 1992 top-tenth 24 49.7 48.9 0.8 107 9 1918 2013,2023 1991 1992 top-tenth 36 48.9 48.9 0.0 92 19 1918 2013 1991 1989 top-third 1988,2004 48 49.0 48.9 0.1 91 16 1927 2023 1991 1992 top-third 60 49.1 48.9 0.2 88 16 1920,1927,1928 2023 1991 1992 top-third 2004,2009