1991-2020 Degrees Fahrenheit 1 43.9 44.0 -0.1 46 29 1969 2015 2011 2010 normal 2 49.8 50.0 -0.2 47 28 1970 2015 2009 2011 normal 2008 3 54.5 54.5 0.0 54 21 1976 2015 2009 2011 top-third 1972,2008 4 57.5 57.3 0.2 57 18 1976 2015 2009 2011 top-third 5 59.0 58.0 1.0 66 9 1976 2015 2009 2011 top-third 2003 6 58.2 57.0 1.2 70 5 1971,1975,1976 2015,2018 2011 2010 top-tenth 2016 7 56.5 55.0 1.5 73 2 1975 2018 2011 2012 top-tenth 2015 8 54.2 52.5 1.7 73 2 1970 2015 2011 2012 top-tenth 9 50.9 49.4 1.5 70 5 1973,1984 2015 2011 2012 top-tenth 10 48.0 46.2 1.8 72 3 1984 2015 2011 2000 top-tenth 2000 11 45.0 43.6 1.4 67 6 1979,1984 2018 2010 2011 top-tenth 2005,2020 12 43.7 42.5 1.2 64 9 1973 2018 2010 2011 top-third 2006,2016 18 48.3 47.3 1.0 66 7 1973 2018 2010 2011 top-tenth 2003,2021 24 43.8 42.5 1.3 67 4 1993 2018 2011 2000 top-tenth 36 43.5 42.4 1.1 63 6 1975 2018 2011 2001 top-tenth 48 43.3 42.3 1.0 62 5 1976 2019,2020 2011 2006 top-tenth 2002,2006 60 42.6 42.2 0.4 52 13 1977 2020,2021 2011 2009 top-third 2009