1991-2020 Degrees Fahrenheit 1 57.1 57.7 -0.6 40 36 1960 2012 1984 1985 normal 2 55.1 54.4 0.7 51 25 1960 2023 1985 1982 top-third 1989 3 51.6 52.2 -0.6 33 42 1978 2017 1985 1982 normal 2013 4 49.8 51.7 -1.9 25 50 1978 2017 1984 1985 bottom-third 1961 5 52.7 52.5 0.2 47 27 1977 2017 1985 1975 normal 6 55.5 54.7 0.8 57 17 1977 2017 1985 1974 top-third 1995 7 58.2 57.8 0.4 57 17 1977 2017 1985 1974 top-third 1997 8 60.9 60.8 0.1 53 21 1977 2017 1985 1974 top-third 1973,1997 9 63.2 63.2 0.0 51 23 1968,1977 2017 1985 1974 top-third 1997,2005 10 65.0 64.8 0.2 54 20 1968,1977 2017 1985 1974 top-third 2000 11 65.7 65.5 0.2 54 20 1977 2017 1985 1974 top-third 2008 12 65.6 65.4 0.2 53 21 1977 2017 1985 1974 top-third 2007,2013 18 62.0 61.8 0.2 51 21 1978 2017 1985 1975 top-third 1951 24 65.2 65.4 -0.2 45 27 1969,1978 2017 1985 1975 normal 1972,1973,1999,2003,2009 36 64.8 65.3 -0.5 30 40 1970 2018 1985 1976 normal 48 64.8 65.3 -0.5 25 43 1970 2020 1985 1976 normal 1962,1997 60 64.7 65.3 -0.6 24 42 1970 2020 1985 1976 normal 1963