1991-2020 Degrees Fahrenheit 1 62.6 66.4 -3.8 11 65 1967 2018 1967 1970 bottom-third 2 59.6 62.3 -2.7 10 66 1961 2019 1967 1970 bottom-third 1967 3 54.7 57.7 -3.0 5 71 1960 2012 1961 1970 bottom-tenth 1950,1975 4 51.1 53.6 -2.5 13 63 1958 2012 1967 1970 bottom-third 1996 5 47.8 50.5 -2.7 12 64 1978 2012 1970 1968 bottom-third 6 46.7 49.0 -2.3 19 56 1978 2012 1970 1968 bottom-third 1962 7 46.8 48.9 -2.1 21 54 1978 2012 1970 1967 bottom-third 1997 8 48.6 50.2 -1.6 30 45 1978 2012 1970 1965 normal 1987,2014 9 51.4 52.4 -1.0 39 36 1977,1978 2017 1970 1957 normal 10 53.8 54.8 -1.0 39 36 1977 2017 1970 1957 normal 1955 11 55.9 56.9 -1.0 37 38 1977 2017 1970 1959 normal 1959 12 57.4 58.3 -0.9 39 36 1977 2017 1970 1957 normal 2003 18 53.4 55.2 -1.8 18 56 1964,1979 2017 1970 1966 bottom-third 1989 24 56.6 58.3 -1.7 17 57 1978 2017 1970 1966 bottom-third 1952,1981,1982 36 56.4 58.3 -1.9 10 63 1970,1979 2018 1970 1967 bottom-third 1960,1966,1977,1982 48 56.1 58.2 -2.1 4 68 1980 2019,2020 1970 1968 bottom-tenth 1964,1966 60 56.2 58.2 -2.0 3 68 1970,1981 2020 1970 1969 bottom-tenth 1967,1968,1969