1991-2020 Degrees Fahrenheit 1 64.6 65.6 -1.0 36 43 1964 1981 1991 1990 normal 2 64.7 64.2 0.5 63 16 1964 2014 1991 1984 top-third 1978 3 64.6 62.9 1.7 72 7 1964 2014 1991 1992 top-tenth 4 62.9 61.8 1.1 67 12 1964 2014 1991 1992 top-third 1993 5 62.2 60.9 1.3 72 7 1964,1975 2014 1991 1992 top-tenth 6 61.4 60.3 1.1 72 7 1950 2014 1991 1992 top-tenth 7 60.8 59.7 1.1 72 7 1950 2014 1991 1992 top-tenth 1997 8 61.0 60.0 1.0 72 7 1949 2014 1991 1992 top-tenth 9 61.5 60.7 0.8 71 8 1949 2014 1991 1992 top-tenth 2013 10 62.0 61.5 0.5 69 10 1949 2014,2016 1991 1984 top-third 1984,2021 11 62.5 62.3 0.2 64 15 1949 2016 1991 1984 top-third 12 62.8 62.8 0.0 59 19 1949 2016 1991 1984 top-third 2004 18 61.3 61.9 -0.6 49 29 1949 2015 1991 1987 normal 1995 24 62.4 62.8 -0.4 53 24 1950 2016 1991 1985 top-third 2005 36 62.3 62.7 -0.4 53 23 1950 2016 1991 1986 top-third 1959 48 62.0 62.7 -0.7 45 30 1951 2017,2018 1991 1987 normal 1981,1985,2012 60 61.9 62.6 -0.7 40 34 1952 2018 1991 1988 normal 1960