1991-2020 Degrees Fahrenheit 1 31.4 32.5 -1.1 43 34 1977 2023 1979 1975 normal 2 35.0 34.9 0.1 53 23 1961 2002 1979 1974 top-third 1960 3 39.3 38.7 0.6 60 16 1977 2002,2016 1979 1974 top-third 1974,2005 4 42.9 43.3 -0.4 52 24 1977 2002 1979 1976 top-third 1976 5 47.6 48.6 -1.0 48 27 1977 2016 1979 1979 normal 1979 6 52.0 53.2 -1.2 47 28 1977 2016 1978 1979 normal 1976 7 55.2 56.7 -1.5 40 35 1977 2017 1978 1979 normal 1962,1986 8 57.0 58.8 -1.8 33 42 1977 2017 1978 1979 normal 2015 9 57.7 59.4 -1.7 34 41 1977 2016 1978 1979 normal 2009 10 57.1 58.9 -1.8 32 43 1977 2016 1978 1979 normal 1969,1985 11 56.1 57.5 -1.4 42 33 1977 2017 1979 1974 normal 12 53.3 55.6 -2.3 20 55 1968 2013 1979 1978 bottom-third 2015 18 53.1 54.7 -1.6 41 32 1941,1964,1968 2017 1979 1975 normal 1958,1960 24 53.2 55.5 -2.3 16 57 1964,1968 2013 1978 1979 bottom-third 1945,1967,1970,1982 36 53.4 55.5 -2.1 19 52 1963,1965 2023 1979 1976 bottom-third 1945 48 53.2 55.5 -2.3 11 58 1964 2023 1971 1979 bottom-third 1959,1981,1982 60 53.3 55.5 -2.2 13 54 1965,1968 2023 1979 1979 bottom-third 1944,1962,1972,1979,1982