1991-2020 Degrees Fahrenheit 1 33.9 38.3 -4.4 21 64 1960 2012 2014 2012 bottom-third 2 24.9 33.4 -8.5 3 82 1978 2012 2014 2013 bottom-tenth 1960 3 23.9 30.7 -6.8 5 80 1978 2012 2014 2013 bottom-tenth 1940 4 26.1 30.7 -4.6 10 75 1978 2012 2014 2013 bottom-third 1959,1962 5 27.8 32.8 -5.0 8 76 1978 2012 2014 2013 bottom-tenth 6 31.8 36.2 -4.4 7 76 1978 2012 2014 2013 bottom-tenth 7 36.2 40.3 -4.1 6 77 1977,1978 2012,2016 2014 2013 bottom-tenth 1970 8 40.6 44.2 -3.6 6 77 1977 2012,2017 2014 2013 bottom-tenth 9 43.8 47.4 -3.6 5 77 1977 2012 2014 2013 bottom-tenth 10 46.6 49.7 -3.1 7 75 1977 2012 2014 2013 bottom-tenth 11 47.9 50.8 -2.9 6 76 1977 2012 2014 2014 bottom-tenth 1959,2014 12 48.1 50.7 -2.6 9 73 1977 2012 2014 2013 bottom-third 1993 18 42.3 45.9 -3.6 3 77 1978 2017 1979 2014 bottom-tenth 24 48.0 50.7 -2.7 2 78 1978 2017 1978 2014 bottom-tenth 1963 36 49.2 50.7 -1.5 21 57 1979 2018 1995 2014 bottom-third 1948,1962,1984,1986 48 50.4 50.6 -0.2 55 21 1980 2019 2010 2014 top-third 1989,2010 60 50.6 50.6 0.0 58 16 1981 2020 2011 2014 top-third 1957,1992,2011