1991-2020 Degrees Fahrenheit 1 39.7 36.1 3.6 112 18 1978 2017 1991 1990 top-third 2 36.6 34.2 2.4 108 22 1978 2023 1991 1990 top-third 1927 3 37.2 34.9 2.3 114 15 1978 1932 1991 1957 top-third 1909,1957 4 38.4 37.4 1.0 107 22 1977 1932 1990 1991 top-third 1975,2006 5 42.1 41.1 1.0 104 25 1977 1932 1990 1991 top-third 1916,1998,2006,2019 6 46.3 45.6 0.7 103 26 1977 1932 1990 1991 top-third 1921,1922,1937,1983 7 50.3 49.7 0.6 103 26 1977 1932 1991 1974 top-third 1919 8 53.5 52.8 0.7 102 27 1977 1932 1991 1974 top-third 9 55.6 54.9 0.7 101 28 1977 1932 1991 1974 top-third 1914 10 56.9 55.8 1.1 109 20 1977 1932 1991 1954 top-third 11 56.9 55.7 1.2 116 13 1977 1932 1991 1942 top-tenth 1909,1942,2006,2016,2019 12 56.0 54.8 1.2 117 12 1977 2017 1991 1937 top-tenth 1923 18 52.8 51.7 1.1 116 12 1918,1977 2017 1991 1950 top-tenth 1923,2006 24 55.2 54.8 0.4 109 19 1978 2017 1991 1955 top-third 1922,1955 36 54.7 54.7 0.0 96 31 1979 2018,2019 1991 1956 top-third 1899,1901,1950,2004 48 54.5 54.7 -0.2 87 39 1980 2020 1991 1957 top-third 1932,1939,1945,2004,2010 60 54.5 54.7 -0.2 87 38 1981 2020 1991 1957 top-third 1932,1943,1949,1953,2001