1991-2020 Degrees Fahrenheit 1 41.5 45.9 -4.4 23 55 1960 2012 1998 2000 bottom-third 2 36.3 40.5 -4.2 20 58 1960 2012 1993 2000 bottom-third 3 34.5 37.2 -2.7 31 47 1979 2012 1996 2000 normal 4 31.2 36.4 -5.2 6 72 1979 2012 1984 2000 bottom-tenth 5 32.5 38.0 -5.5 5 73 1979 2012 1979 2000 bottom-tenth 6 37.3 41.2 -3.9 6 72 1979 2012 1979 2000 bottom-tenth 2014 7 42.4 45.3 -2.9 13 65 1979 2016 1996 2000 bottom-third 1970,2014 8 47.8 49.4 -1.6 30 48 1979 2012 1997 2000 normal 1956,1984 9 51.4 52.8 -1.4 30 47 1979 2012 1997 2000 normal 10 53.5 55.1 -1.6 29 48 1962,1979 2012 1997 2000 normal 11 54.9 56.1 -1.2 33 44 1962 2012 1997 2000 normal 1961 12 55.0 56.1 -1.1 35 42 1962 2012 1998 2000 normal 1961 18 51.7 51.1 0.6 62 15 1979 2017 1998 2000 top-third 24 56.4 56.0 0.4 60 16 1979 2013,2017 1999 2000 top-third 36 56.9 56.0 0.9 70 5 1979 2013 2000 2001 top-tenth 2002,2008 48 56.3 56.0 0.3 56 18 1980 2002 2000 1992 top-third 2006 60 55.9 56.0 -0.1 50 23 1962 2003 2000 1992 top-third 2012