1991-2020 Degrees Fahrenheit 1 50.1 56.1 -6.0 3 82 1940 2017 1943 1949 bottom-tenth 2 44.8 50.8 -6.0 2 83 1940 2012 1940 1949 bottom-tenth 3 41.9 46.4 -4.5 6 79 1940 2012 1947 1949 bottom-tenth 4 42.6 43.6 -1.0 46 39 1940 2023 1948 1949 normal 1959,2009 5 42.0 42.9 -0.9 49 36 1940 2012 1948 1949 normal 6 42.8 43.7 -0.9 47 37 1940 2012 1948 1949 normal 1975 7 45.6 45.8 -0.2 57 27 1940 2012 1948 1949 top-third 2010,2013 8 48.2 48.9 -0.7 51 33 1940 2012 1948 1949 normal 1946,1983,1997 9 51.5 52.0 -0.5 53 31 1977 2017 1948 1949 normal 1953 10 54.4 54.7 -0.3 60 24 1977 2017 1948 1949 top-third 1953 11 56.3 56.5 -0.2 61 22 1977 2012 1948 1949 top-third 1953,1954,1976 12 57.0 57.3 -0.3 57 26 1977 2012 1948 1949 top-third 18 53.0 52.7 0.3 64 18 1941 2017 1949 1950 top-third 1954 24 57.1 57.2 -0.1 62 19 1978 2017 1949 1950 top-third 1954,2016 36 56.4 57.2 -0.8 45 34 1979 2013 1949 1950 normal 1987,1989,1990 48 56.3 57.2 -0.9 41 36 1964,1980 2023 1949 1950 normal 1976,1988,1989 60 56.2 57.1 -0.9 33 42 1965 2023 1949 1949 normal 1949,1974,1975,1987,1988