1991-2020 Degrees Fahrenheit 1 47.9 46.0 1.9 55 22 1960 2012 2008 2007 top-third 2 43.0 42.1 0.9 52 25 1960 1976 2008 2000 top-third 3 39.1 39.8 -0.7 40 37 1978 1990 2004 2008 normal 4 38.8 39.5 -0.7 41 36 1978 2012 2004 2008 normal 1985 5 39.7 40.9 -1.2 32 44 1977 2012 2003 2008 normal 1962,2013 6 42.4 43.6 -1.2 33 43 1977 2012 2003 2008 normal 1962 7 46.5 47.1 -0.6 37 38 1977 2017 2004 2008 normal 8 49.8 50.6 -0.8 34 41 1977 2017 2004 2008 normal 2011 9 52.5 53.3 -0.8 29 46 1977 2017 2004 2008 normal 1955 10 54.5 55.2 -0.7 32 43 1977 2017 2004 2008 normal 1955 11 55.2 56.1 -0.9 30 45 1977 2017 2004 2008 normal 1973 12 55.3 56.2 -0.9 29 46 1977 2012,2017,2020 2004 2008 normal 1965,1985 18 51.8 51.9 -0.1 47 28 1978 2017 2005 2008 normal 2005 24 56.3 56.1 0.2 56 18 1978 2017 2007 2008 top-third 1955,1988,2007,2016 36 56.2 56.1 0.1 52 21 1979 2018 2006 2008 top-third 1976,1994 48 56.3 56.1 0.2 59 13 1980 2020 2007 2008 top-third 1955,1956,1994,2012 60 56.3 56.0 0.3 62 9 1981 2020 2008 1992 top-third 1954,2016,2017