1991-2020 Degrees Fahrenheit 1 53.1 51.6 1.5 62 32 1924 1977 1920 1919 normal 2 47.3 45.1 2.2 78 16 1909 1977 1920 1915 top-third 1952 3 38.8 38.1 0.7 67 25 1950 2010 1920 1915 top-third 4 32.9 31.1 1.8 77 15 1917,1950 1998 1920 1915 top-third 5 28.3 26.0 2.3 82 10 1950 1998 1920 1921 top-third 2017 6 25.8 23.6 2.2 80 10 1950 1998 1920 1921 top-third 7 25.8 24.0 1.8 76 12 1979 2012 1920 1921 top-third 2007 8 28.6 26.3 2.3 77 10 1920 2012 1920 1921 top-third 2002 9 32.0 29.4 2.6 76 9 1920 2012 1920 1921 top-third 1999 10 35.3 32.8 2.5 76 8 1920 2012 1920 1921 top-tenth 11 38.0 35.7 2.3 76 8 1920 2012 1920 1921 top-tenth 12 39.8 37.8 2.0 73 9 1950,1951 2012 1916 1921 top-third 18 32.2 33.1 -0.9 50 29 1951 1999 1916 1915 normal 1976 24 -99 37.8 -99 -99 -99 1951 1999 normal 36 -99 37.8 -99 -99 -99 1952 2000 normal 48 -99 37.7 -99 -99 -99 1952 2001 normal 60 -99 37.7 -99 -99 -99 1953 2002 normal