1991-2020 Degrees Fahrenheit 1 26.7 38.3 -11.6 2 83 1960 2012 1960 1983 bottom-tenth 2 29.2 33.4 -4.2 15 70 1978 2012 1982 1983 bottom-third 1940 3 25.4 30.7 -5.3 10 75 1978 2012 1982 1983 bottom-third 4 23.9 30.7 -6.8 4 81 1978 2012 1978 1983 bottom-tenth 5 27.7 32.8 -5.1 6 78 1978 2012 1982 1983 bottom-tenth 1982 6 32.0 36.2 -4.2 8 75 1978 2012 1982 1983 bottom-tenth 7 36.9 40.3 -3.4 10 73 1977,1978 2012,2016 1982 1983 bottom-third 8 41.8 44.2 -2.4 16 67 1977 2012,2017 1982 1983 bottom-third 1943 9 45.8 47.4 -1.6 24 58 1977 2012 1982 1983 bottom-third 1952,1964 10 48.2 49.7 -1.5 27 55 1977 2012 1982 1983 bottom-third 11 48.9 50.8 -1.9 20 62 1977 2012 1982 1983 bottom-third 1958,1964,1975,1996 12 48.7 50.7 -2.0 18 64 1977 2012 1982 1983 bottom-third 18 45.3 45.9 -0.6 51 29 1978 2017 1983 1976 normal 1976,1987,1989,2009 24 49.8 50.7 -0.9 37 43 1978 2017 1983 1976 normal 1949,1953,1973,1976 36 49.2 50.7 -1.5 21 57 1979 2018 1982 1983 bottom-third 1948,1962,1986,2015 48 49.2 50.6 -1.4 22 54 1980 2019 1983 1976 bottom-third 1972 60 49.0 50.6 -1.6 16 58 1981 2020 1983 1983 bottom-third 1972,1983