1991-2020 Degrees Fahrenheit 1 46.3 47.2 -0.9 23 38 2018 2010 2007 2010 normal 2 39.9 41.3 -1.4 23 38 1965 2012 2003 2010 normal 3 35.1 36.3 -1.2 28 33 1978 2012 2008 2010 normal 4 31.6 33.4 -1.8 20 41 1978 2012 2003 2010 bottom-third 5 30.7 32.7 -2.0 17 44 1978 2012 2003 2010 bottom-third 6 32.5 33.8 -1.3 24 36 2014 2012 2009 2010 normal 1975 7 35.5 36.3 -0.8 28 32 1978 2012 2009 2010 normal 1972 8 38.9 39.7 -0.8 28 32 1977,1978 2012 2009 2010 normal 9 42.9 43.1 -0.2 35 25 1978 2012 2009 2010 normal 1992 10 46.1 46.0 0.1 38 22 1977 2012 2009 2010 normal 1985,1995,2004 11 48.2 48.1 0.1 39 21 1978 2012 2009 2010 normal 1992,1995 12 49.3 49.0 0.3 43 17 1982 2012 2010 2008 top-third 2019 18 44.9 43.9 1.0 51 8 1979 2017 2010 2008 top-third 2006,2008,2021 24 49.2 48.9 0.3 43 16 1978 2017 2010 2008 top-third 36 48.8 48.9 -0.1 37 21 1979 2013 2005 2010 normal 48 49.1 48.9 0.2 42 15 1980 2013 2010 2009 top-third 2007,2017 60 49.1 48.9 0.2 40 16 1982 2020 2007 2010 top-third 2001