1901-2000 Degrees Fahrenheit 1 25.9 31.5 -5.6 22 108 1978 2017 1980 1981 bottom-third 2 22.9 29.6 -6.7 12 118 1979 2017 1979 1981 bottom-tenth 3 24.8 30.3 -5.5 10 119 1978 1932 1979 1981 bottom-tenth 1902 4 29.8 33.3 -3.5 14 115 1977 1932 1979 1981 bottom-third 5 34.6 37.8 -3.2 14 115 1977 1932 1979 1981 bottom-third 6 39.7 42.7 -3.0 13 116 1977 1932 1979 1981 bottom-tenth 7 44.4 47.2 -2.8 12 117 1977 1932 1979 1981 bottom-tenth 1902 8 48.4 50.9 -2.5 12 117 1977 1932 1979 1981 bottom-tenth 1936,1970 9 51.2 53.3 -2.1 15 114 1977 1932 1979 1981 bottom-third 10 52.0 54.3 -2.3 7 122 1977 1932 1979 1981 bottom-tenth 1979 11 52.6 54.1 -1.5 16 113 1918 1932 1979 1981 bottom-third 2015 12 51.7 53.1 -1.4 19 110 1918 2017 1979 1981 bottom-third 1925 18 48.7 49.6 -0.9 24 104 1905 2017 1980 1981 bottom-third 1936,1961,1964 24 52.4 53.1 -0.7 30 98 1905 2013,2017 1980 1981 bottom-third 1917,1964 36 52.3 53.0 -0.7 19 108 1979 2013 1981 1976 bottom-third 1964,1968 48 51.9 53.0 -1.1 7 119 1980 2019 1980 1981 bottom-tenth 1918 60 51.9 53.0 -1.1 6 119 1981 2020 1981 1979 bottom-tenth 1979