1991-2020 Degrees Fahrenheit 1 52.8 51.4 1.4 58 18 1972 2017 2013 2012 top-third 2 57.5 57.1 0.4 59 17 1972 2017 2013 2012 top-third 1990,1999 3 60.9 61.5 -0.6 41 35 1972 2017 2013 2012 normal 1989,2004 4 63.4 64.0 -0.6 38 38 1962 1949,2007,2016,2017 2009 2013 normal 5 64.1 64.4 -0.3 40 36 1958 1949 2009 2013 normal 6 62.9 63.3 -0.4 44 31 1958 1949 2009 2013 normal 1994 7 60.5 60.9 -0.4 41 33 1972 1949,2010 2009 2013 normal 1970 8 56.5 57.8 -1.3 21 53 1972 2010,2012 2009 2013 bottom-third 2009 9 52.9 54.4 -1.5 19 55 1972 2012 2003 2013 bottom-third 1980,1993,1996 10 49.9 51.6 -1.7 14 59 1978 2012 2003 2013 bottom-third 1963 11 47.9 49.7 -1.8 14 59 1978 2012 2003 2013 bottom-third 1950,1961,1966,1986,1992,1996 12 47.1 49.0 -1.9 13 60 1956,1978 2012 2003 2013 bottom-third 1950,1971 18 52.6 53.8 -1.2 25 47 1978 2012 2003 2013 normal 1957,1994,2001 24 48.2 49.0 -0.8 37 33 1978 2017 2009 2013 normal 1974,1990 36 49.6 49.0 0.6 59 8 1972 2012 2011 2013 top-third 48 49.4 49.0 0.4 56 8 1965,1972 2013 2011 2013 top-third 2020 60 49.7 48.9 0.8 58 3 1966 2020 2012 2013 top-tenth 2012,2016,2021