1991-2020 Degrees Fahrenheit 1 46.9 48.7 -1.8 40 45 1940 2017 1948 1955 normal 2 48.3 49.4 -1.1 38 47 1984 2022 1954 1955 normal 1969 3 50.7 52.0 -1.3 36 49 1977 2017 1954 1955 normal 4 54.8 56.0 -1.2 35 50 1977 2017 1953 1955 normal 1968,1991,2009 5 59.8 60.6 -0.8 48 37 1977 2017 1954 1955 normal 6 63.4 64.7 -1.3 39 46 1977 2017 1953 1955 normal 1976 7 66.2 67.5 -1.3 39 46 1977 2017 1954 1955 normal 1954 8 67.7 69.3 -1.6 26 58 1977 2017 1951 1955 bottom-third 1945,1963,1967,1978,1979,1983,1997 9 68.6 69.9 -1.3 36 48 1977 2017 1953 1955 normal 1953,1963,1970 10 68.7 69.6 -0.9 43 41 1977 2012,2017 1953 1955 normal 11 67.9 68.6 -0.7 49 35 1977 2017 1953 1955 normal 1971,1981,1985 12 66.4 67.3 -0.9 47 37 1984 2017 1953 1955 normal 1947,1972 18 66.1 66.4 -0.3 63 21 1984 2017 1954 1955 top-third 1986 24 67.2 67.3 -0.1 65 18 1962 2017 1954 1955 top-third 2005,2016 36 67.1 67.2 -0.1 64 18 1961 2018 1955 1956 top-third 2009 48 66.7 67.2 -0.5 52 29 1962 2019 1954 1955 normal 60 66.7 67.1 -0.4 52 28 1962,1963 2020 1955 1956 normal