1991-2020 Degrees Fahrenheit 1 52.7 51.2 1.5 57 19 1968 2018 1998 1999 top-third 2 49.6 49.4 0.2 45 30 1977,1978 1950 1996 1999 normal 3 49.3 49.6 -0.3 43 32 1977 2017 1996 1999 normal 1965,1983 4 51.4 51.1 0.3 48 26 1977 2017 1998 1999 normal 1983 5 54.3 54.1 0.2 49 25 1977 2017 1998 1999 normal 6 57.6 57.8 -0.2 46 28 1977 2017 1998 1999 normal 1971 7 61.5 61.2 0.3 53 21 1977 2017 1998 1999 top-third 8 64.0 63.8 0.2 51 23 1977 2017 1998 1999 top-third 9 65.6 65.6 0.0 50 24 1977 2017 1998 1999 top-third 10 66.2 66.3 -0.1 51 23 1977 2017 1998 1999 top-third 1955,1992,2006,2011 11 66.4 66.1 0.3 56 18 1977 2017 1998 1999 top-third 1955,1986 12 65.4 65.4 0.0 51 23 1977 2017 1998 1999 top-third 18 63.7 62.8 0.9 64 8 1977 2017 1999 2000 top-third 24 66.2 65.4 0.8 64 8 1977 2017 1999 2000 top-third 36 65.5 65.3 0.2 58 12 1970 2018 1999 1992 top-third 48 65.2 65.3 -0.1 52 16 1970 2019,2020 1999 1992 top-third 1958,1989,2009,2012,2016 60 65.2 65.3 -0.1 51 15 1970 2020 1999 1991 top-third 1955,1958,1959,1991,2008