1991-2020 Degrees Fahrenheit 1 43.2 51.7 -8.5 4 81 1978 2017 1947 1967 bottom-tenth 2 44.1 49.8 -5.7 8 77 1978 2017 1963 1967 bottom-tenth 1947 3 45.5 49.6 -4.1 9 76 1978 2017 1964 1967 bottom-third 4 48.3 51.3 -3.0 16 69 1978 2017 1964 1967 bottom-third 5 51.9 54.5 -2.6 13 72 1977 2017 1964 1967 bottom-third 1964 6 55.4 58.5 -3.1 6 79 1977 2017 1940 1967 bottom-tenth 1982 7 58.8 62.1 -3.3 5 80 1977 2017 1968 1967 bottom-tenth 8 61.4 64.8 -3.4 3 82 1977 2017 1968 1967 bottom-tenth 9 63.5 66.6 -3.1 3 81 1977 2017 1968 1967 bottom-tenth 10 64.2 67.3 -3.1 3 81 1977 2017 1968 1967 bottom-tenth 11 64.8 67.2 -2.4 6 78 1977 2017 1962 1967 bottom-tenth 2010 12 64.7 66.5 -1.8 21 63 1977 2017 1963 1967 bottom-third 18 61.9 63.8 -1.9 15 69 1984 2017 1961 1967 bottom-third 1948,1974,1983 24 64.7 66.4 -1.7 16 67 1978 2017 1963 1967 bottom-third 1974,1979 36 64.8 66.4 -1.6 15 67 1979,1984 2018 1963 1967 bottom-third 1971,1986 48 65.2 66.4 -1.2 27 54 1980 2019 1964 1967 bottom-third 1974,1991,1994,1996 60 65.4 66.3 -0.9 45 35 1980 2020 1967 1960 normal 1951,1960,1989,1990,1992,1993,1995,1996,1998