1991-2020 Degrees Fahrenheit 1 55.1 59.7 -4.6 26 66 1978 2017 1934 1933 bottom-third 2 55.7 57.8 -2.1 38 53 1978 2017 1934 1933 normal 1955,1980 3 58.7 57.7 1.0 72 19 1978 2017 1933 1934 top-third 2005 4 60.0 59.3 0.7 72 19 1977 2017 1933 1934 top-third 5 62.8 62.2 0.6 68 18 1977 2017 1933 1934 top-third 2006 6 66.1 65.5 0.6 69 17 1977 2017 1933 1934 top-third 1986 7 68.6 68.4 0.2 67 19 1977 2017 1933 1934 top-third 1995 8 70.5 70.5 0.0 66 19 1977 2017 1933 1934 top-third 2019 9 71.6 72.0 -0.4 61 24 1977 2017 1933 1934 top-third 1989 10 72.5 72.7 -0.2 63 22 1977 2017 1933 1934 top-third 1992 11 72.3 72.6 -0.3 60 24 1977 2017 1933 1934 top-third 2004,2007 12 71.7 72.0 -0.3 61 23 1977 2017 1933 1934 top-third 1952 18 68.5 69.8 -1.3 41 40 1978 2017 1934 1934 normal 2002 24 70.3 71.9 -1.6 29 51 1978 2017 1934 1934 normal 1954,1976,2015 36 -99 72.0 -99 -99 -99 1979 2018 normal 48 -99 71.9 -99 -99 -99 1980 2019 normal 60 -99 72.0 -99 -99 -99 1980,1981 2020 normal