1991-2020 Degrees Fahrenheit 1 64.6 63.6 1.0 62 13 1974 2007 2012 2013 top-third 2 64.6 64.6 0.0 51 24 1950 2011 2009 2013 top-third 1998 3 64.3 63.4 0.9 65 10 1992 2011 2009 2013 top-third 4 60.8 60.6 0.2 58 17 1950 2012 2013 2012 top-third 2005,2017 5 57.5 57.0 0.5 62 13 1983 2012 2013 2012 top-third 2003,2017 6 54.6 53.4 1.2 70 5 1975 2012 2013 2012 top-tenth 2007 7 50.9 49.3 1.6 70 5 1979 2020 2013 2012 top-tenth 8 47.4 45.3 2.1 71 4 1984 2018 2013 2012 top-tenth 9 -99 42.2 -99 -99 -99 1979 2018 normal 10 -99 41.1 -99 -99 -99 1973,1992 2018 normal 11 -99 41.3 -99 -99 -99 1992 2018 normal 12 -99 42.6 -99 -99 -99 1992 2018 normal 18 -99 46.1 -99 -99 -99 1984 2018 normal 24 -99 42.5 -99 -99 -99 1993 2018 normal 36 -99 42.5 -99 -99 -99 1975 2018 normal 48 -99 42.3 -99 -99 -99 1976 2019 normal 60 -99 42.2 -99 -99 -99 1977 2020 normal