1991-2020 Degrees Fahrenheit 1 28.3 35.3 -7.0 25 100 1933 2017 1979 1987 bottom-third 2 22.4 31.6 -9.2 17 108 1933 2005 1979 1987 bottom-third 3 23.9 30.5 -6.6 24 100 1933 1981 1979 1987 bottom-third 1964 4 27.6 32.8 -5.2 30 94 1933 1981 1979 1987 bottom-third 1975 5 33.2 36.9 -3.7 40 84 1933 2017 1979 1987 bottom-third 1918 6 38.6 42.0 -3.4 45 79 1917,1933 2017 1979 1987 normal 1908,1977 7 43.3 46.9 -3.6 46 78 1917 2017 1979 1987 normal 1901,1976 8 47.2 50.9 -3.7 42 82 1917 2017 1979 1987 normal 1947,1975 9 50.0 53.4 -3.4 45 79 1913 2017 1979 1987 normal 1922,1963,1975,1977 10 51.0 54.2 -3.2 50 74 1913,1917 2017 1979 1987 normal 1927 11 51.3 54.0 -2.7 63 61 1913 2017 1985 1987 normal 1945,1951,1985 12 50.2 53.3 -3.1 56 68 1913 2018 1984 1987 normal 1902,1927,1947,1951,1984 18 47.0 49.5 -2.5 72 51 1913 2018 1985 1987 normal 1955,1970 24 51.3 53.3 -2.0 80 43 1913,1914 2018 1985 1987 normal 36 52.0 53.2 -1.2 89 33 1914,1915,1918 2019 1986 1987 top-third 1991 48 51.6 53.2 -1.6 84 37 1920 2018 1987 1987 top-third 1987,1991 60 51.3 53.1 -1.8 78 42 1917 2019 1981 1987 normal