1991-2020 Degrees Fahrenheit 1 47.9 52.1 -4.2 23 106 1917 1934 1915 1914 bottom-third 2 43.7 47.4 -3.7 21 108 1917 2012 1909 1915 bottom-third 3 41.8 43.9 -2.1 71 58 1917 2012 1915 1911 normal 4 39.3 40.2 -0.9 91 38 1899 1992 1915 1910 top-third 1926 5 34.8 38.0 -3.2 40 89 1899 1992 1915 1915 bottom-third 1915,1950,1956,1978,1979 6 33.7 36.3 -2.6 39 89 1917 1934,1992 1915 1911 bottom-third 1902,1930,1939,1985 7 34.1 36.3 -2.2 48 79 1899 2000 1915 1914 normal 1896,1914,1953,1968,2010 8 35.7 37.5 -1.8 52 75 1899 1934 1915 1911 normal 1918,1921,1955,1988 9 37.8 40.0 -2.2 41 86 1899 1934 1915 1911 bottom-third 1896,1945,1956 10 40.0 42.7 -2.7 24 103 1917 1934 1914 1915 bottom-third 1914,1942,2010 11 42.0 45.2 -3.2 15 112 1899 1934 1913 1915 bottom-third 1897,1930,1952 12 43.0 46.6 -3.6 10 117 1917 1934 1913 1915 bottom-tenth 1952 18 39.4 43.2 -3.8 8 118 1899 2017 1913 1915 bottom-tenth 1900,1985 24 43.6 46.6 -3.0 15 110 1917 2017 1914 1915 bottom-third 1897,1905 36 43.6 46.6 -3.0 15 108 1914 2018 1915 1912 bottom-third 1898,1906,1909,1924 48 43.1 46.6 -3.5 6 115 1899,1915,1917 2018 1915 1914 bottom-tenth 1920 60 42.9 46.5 -3.6 2 117 1917 2018 1916 1915 bottom-tenth