1991-2020 Degrees Fahrenheit 1 37.2 38.3 -1.1 43 52 1909 1987 1997 2006 normal 2 31.7 31.1 0.6 64 29 1950 2010 2004 2006 top-third 3 22.0 24.0 -2.0 49 44 1923 1987 1997 2006 normal 1963 4 18.9 19.3 -0.4 64 29 1950 2012 2004 2006 top-third 5 18.7 17.7 1.0 73 17 1950,2014 2012 2005 2006 top-third 6 20.4 19.2 1.2 75 13 1920 2012 2005 2006 top-third 7 22.9 22.4 0.5 69 18 1920 2012 2004 2006 top-third 8 26.7 26.4 0.3 68 17 1920 2012 2004 2006 top-third 9 30.7 30.5 0.2 68 16 1920 2012 2005 2006 top-third 2005 10 34.5 33.9 0.6 69 15 1920 2012 2005 2006 top-third 2020 11 37.0 36.4 0.6 67 15 1951 2012 2005 2006 top-third 12 38.4 37.6 0.8 69 13 1951 2012 2005 2006 top-third 1981 18 33.3 31.4 1.9 74 5 1951 1999,2017 2006 2000 top-tenth 24 39.1 37.6 1.5 72 5 1951 2017 2006 2000 top-tenth 36 38.3 37.5 0.8 63 9 1952 2000 2006 2002 top-third 2008,2022 48 38.1 37.5 0.6 60 7 1952 2001 1999 2002 top-tenth 60 -99 37.4 -99 -99 -99 1953 2002 normal