1991-2020 Degrees Fahrenheit 1 46.1 51.2 -5.1 13 81 1924 1977 1909 1915 bottom-third 2 41.0 44.7 -3.7 16 78 1909 1977 1909 1915 bottom-third 3 32.5 37.7 -5.2 8 84 1950 2010 1909 1915 bottom-tenth 4 25.0 30.8 -5.8 11 81 1917 1998 1909 1915 bottom-third 5 19.2 25.6 -6.4 8 84 1950 1998 1912 1915 bottom-tenth 1967 6 17.9 23.2 -5.3 12 78 1950,1979 1998 1912 1915 bottom-third 1918 7 19.0 23.7 -4.7 13 75 1979 2012 1912 1915 bottom-third 1971,1972 8 22.0 25.9 -3.9 16 71 1920 2012 1912 1915 bottom-third 9 25.5 29.1 -3.6 15 70 1920 2012 1913 1915 bottom-third 1913,1971,1978,1994 10 29.1 32.5 -3.4 15 69 1920 2012 1913 1915 bottom-third 1989 11 32.0 35.4 -3.4 13 71 1920 2012 1913 1915 bottom-third 1972 12 33.8 37.5 -3.7 10 72 1979 2012 1912 1915 bottom-third 18 30.2 32.7 -2.5 23 56 1951 1999 1914 1915 bottom-third 1914,1959,1973,1994 24 35.9 37.5 -1.6 30 47 1951 1999,2017 1914 1915 normal 1923,1974,1996 36 36.0 37.4 -1.4 29 43 1952 2000 1914 1915 normal 1962,1975,1978 48 35.5 37.4 -1.9 20 47 1952,1953 2001 1915 1916 bottom-third 1974,1982 60 35.1 37.3 -2.2 5 58 1970 2002 1916 1915 bottom-tenth 1959,1960,1972