1991-2020 Degrees Fahrenheit 1 46.3 52.7 -6.4 7 86 1947 1982 1966 1965 bottom-tenth 2 42.1 46.3 -4.2 7 86 1947 2010 1956 1966 bottom-tenth 1943 3 35.9 40.0 -4.1 10 83 1950 2010 1956 1966 bottom-third 1939,1997 4 29.3 34.6 -5.3 5 88 1934 2010 1950 1966 bottom-tenth 5 27.3 31.0 -3.7 15 78 1934 2012 1963 1966 bottom-third 6 26.2 29.9 -3.7 14 77 2014 2012 1963 1966 bottom-third 1970 7 27.1 30.7 -3.6 12 79 1934 2012 1963 1966 bottom-third 1971 8 29.5 32.7 -3.2 10 81 1934 2012 1963 1966 bottom-third 1950,1979 9 32.5 35.6 -3.1 11 80 1934 2012 1963 1966 bottom-third 1982 10 35.6 38.7 -3.1 10 81 1934 2012 1965 1966 bottom-third 1935,1965 11 38.6 41.2 -2.6 15 76 1934 2012 1965 1966 bottom-third 1977,1982 12 40.5 42.9 -2.4 17 74 1934 2012 1966 1966 bottom-third 1937,1950,1952,1957,1966 18 36.7 38.5 -1.8 31 58 2015 1999 1966 1964 normal 1977 24 40.5 42.8 -2.3 11 78 1935 2017 1966 1965 bottom-third 1947,1959,1960,1971,1978 36 40.4 42.8 -2.4 6 81 1936 2000 1938 1966 bottom-tenth 48 41.1 42.9 -1.8 28 57 1937 2013 1966 1965 bottom-third 1941,1945,1965,1973 60 40.8 42.8 -2.0 8 75 1938 2002 1963 1966 bottom-tenth 1936,1981,1997