1991-2020 Degrees Fahrenheit 1 39.9 37.7 2.2 68 17 1979 2017 2000 1998 top-third 1957 2 37.2 36.5 0.7 63 22 1978 2023 2000 1999 top-third 1974 3 35.3 37.6 -2.3 35 50 1963 2023 1996 2000 normal 1967,1971 4 37.9 40.2 -2.3 30 54 1977 2012 1996 2000 normal 5 42.0 43.8 -1.8 32 52 1977 2017 1996 2000 normal 6 46.1 48.3 -2.2 23 61 1977 2017 1996 2000 bottom-third 1996 7 50.2 52.4 -2.2 18 66 1977 2017 1994 2000 bottom-third 1948,2003 8 53.2 55.7 -2.5 13 71 1977 2017 1982 2000 bottom-third 1959 9 55.6 57.8 -2.2 15 68 1977 2017 1982 2000 bottom-third 10 56.6 58.6 -2.0 15 68 1977 2012 1982 2000 bottom-third 1955,1966 11 56.4 58.4 -2.0 18 65 1977 2012 1993 2000 bottom-third 1945,1993 12 55.9 57.3 -1.4 32 51 1977 2012 1997 2000 normal 1983,2014 18 53.4 54.2 -0.8 47 35 1941 2017 1997 2000 normal 1947,1984,1995 24 56.5 57.2 -0.7 51 30 1968 2013 1998 2000 normal 1972,1987 36 57.0 57.2 -0.2 61 18 1963,1968,1979 2013 1999 2000 top-third 2010 48 57.0 57.2 -0.2 58 19 1964 2023 2000 2000 top-third 2000,2016 60 56.7 57.1 -0.4 49 26 1965,1967,1968 2020,2023 1998 2000 normal