1991-2020 Degrees Fahrenheit 1 10.1 20.7 -10.6 5 81 2014 1998 1967 1978 bottom-tenth 2 6.7 18.5 -11.8 1 85 1979 1987 1979 1978 lowest 3 9.5 19.6 -10.1 1 85 1979 1998 1979 1978 lowest 4 15.3 23.4 -8.1 1 85 1979 2002 1979 1978 lowest 5 22.2 28.6 -6.4 3 83 1977,1978 2002 1978 1976 bottom-tenth 6 29.7 34.5 -4.8 5 81 1978 2002,2012,2017 1978 1976 bottom-tenth 7 35.8 39.8 -4.0 6 80 1978 2002 1978 1976 bottom-tenth 8 40.2 44.1 -3.9 4 82 1978 2012 1978 1977 bottom-tenth 1951,1977 9 43.3 46.9 -3.6 6 80 1978 2012 1978 1977 bottom-tenth 1951,1982 10 45.2 48.2 -3.0 10 76 1994 2017 1978 1977 bottom-third 1977 11 45.2 48.1 -2.9 7 79 1951 2017 1968 1978 bottom-tenth 1963,1967,1982,2014 12 43.9 46.9 -3.0 8 77 1951 2017 1968 1978 bottom-tenth 1946,1968 18 38.8 42.7 -3.9 2 83 1952 2017 1952 1978 bottom-tenth 1951 24 44.4 46.9 -2.5 11 73 1952 2017 1973 1978 bottom-third 1971,1972,1980 36 44.5 46.9 -2.4 7 76 1953 2013,2018 1973 1978 bottom-tenth 48 44.8 46.9 -2.1 11 71 1968 2013,2019 1973 1978 bottom-third 1951 60 44.9 46.9 -2.0 11 70 1970 2002 1974 1978 bottom-third 1966,1981,1982,1997