1991-2020 Degrees Fahrenheit 1 69.3 72.8 -3.5 7 68 1954 1962 1971 1970 bottom-tenth 2 66.9 68.6 -1.7 15 60 1997 1955 1971 1970 bottom-third 3 63.3 65.0 -1.7 12 63 1971 2012 1971 1970 bottom-third 2014 4 59.4 61.5 -2.1 13 62 1971 2012 1971 1970 bottom-third 2005 5 57.8 58.8 -1.0 29 45 1978 2017 1971 1967 normal 6 57.5 57.3 0.2 55 19 1978 2017 1971 1967 top-third 1953,1954,1967,1975,2000 7 57.0 57.1 -0.1 46 27 1977 2017 1971 1967 normal 1990 8 58.6 58.2 0.4 55 18 1977 2017 1971 1957 top-third 1955 9 60.8 60.2 0.6 58 15 1968 2017 1971 1957 top-third 10 62.7 62.3 0.4 57 16 1968 2017 1971 1957 top-third 2000,2006,2008 11 64.3 64.2 0.1 54 19 1968 2017 1971 1957 top-third 1986,2008 12 65.6 65.4 0.2 55 18 1968 2017 1971 1957 top-third 1986,2000,2008 18 62.0 62.7 -0.7 35 37 1970 2017 1971 1958 normal 1973,1996,2005 24 64.8 65.4 -0.6 35 36 1969 2017 1971 1958 normal 2004 36 64.3 65.3 -1.0 15 54 1970 2019 1971 1963 bottom-third 1984,1994,1998 48 64.1 65.3 -1.2 10 57 1971 2020 1971 1965 bottom-third 1964 60 63.6 65.3 -1.7 3 62 1970 2020 1971 1969 bottom-tenth 1968,1969