1991-2020 Degrees Fahrenheit 1 47.5 51.7 -4.2 9 71 1976 1985 1967 1968 bottom-third 2 53.9 56.8 -2.9 11 69 1976 1985 1967 1968 bottom-third 1957,1966 3 58.9 62.1 -3.2 6 74 1976 1985 1967 1968 bottom-tenth 4 63.2 66.4 -3.2 5 75 1976 2007 1967 1968 bottom-tenth 1952 5 66.5 69.2 -2.7 8 72 1967 2016 1967 1968 bottom-tenth 1963 6 68.1 70.5 -2.4 10 70 1967 2010 1967 1968 bottom-third 1979,1982 7 67.9 70.3 -2.4 9 70 1967 2010 1967 1968 bottom-third 1979,1992 8 67.0 69.2 -2.2 14 65 1967 2010 1967 1968 bottom-third 1950,1982 9 64.5 67.3 -2.8 5 74 1967 2010 1967 1968 bottom-tenth 1962 10 62.2 65.1 -2.9 8 71 1967 2016 1967 1968 bottom-tenth 1963,1979 11 59.9 63.0 -3.1 5 74 1967 1990,2017 1967 1968 bottom-tenth 1963 12 58.2 61.5 -3.3 4 75 1967 2016 1967 1968 bottom-tenth 18 61.8 64.5 -2.7 8 71 1967 2017 1968 1965 bottom-tenth 1978 24 58.6 61.5 -2.9 6 72 1967 2017 1968 1966 bottom-tenth 1978 36 58.3 61.4 -3.1 1 76 1969 2018 1969 1968 lowest 48 58.3 61.4 -3.1 1 75 1969 2019 1969 1968 lowest 60 58.5 61.4 -2.9 2 73 1967 2020 1967 1968 bottom-tenth 1964,1970