1991-2020 Degrees Fahrenheit 1 39.1 30.5 8.6 76 2 1979 2006 1988 1989 top-tenth 2 37.8 32.2 5.6 76 2 1984 1992 1988 1989 top-tenth 3 40.7 36.3 4.4 76 2 1977 2002 1988 1989 top-tenth 4 44.0 41.6 2.4 70 8 1977 2002 1988 1989 top-tenth 5 49.5 47.2 2.3 70 8 1977 2022 1988 1955 top-tenth 6 54.7 52.4 2.3 73 5 1977 2022 1988 1955 top-tenth 7 58.0 56.3 1.7 68 9 1977 1955 1988 1955 top-third 2016 8 60.3 58.7 1.6 67 10 1977 1955 1988 1964 top-third 1964 9 61.3 59.5 1.8 70 7 1977 2002,2013 1988 1955 top-tenth 10 60.7 59.2 1.5 68 9 1962 2002,2013 1988 1955 top-third 2006 11 59.2 57.9 1.3 66 11 1962 2013 1988 1964 top-third 2016 12 56.9 56.1 0.8 64 13 1979 2013 1988 1988 top-third 1988 18 55.2 54.8 0.4 59 18 1979 2013 1988 1955 top-third 2016 24 56.9 56.0 0.9 66 10 1962 2013 1988 1955 top-third 1992,2014 36 56.6 56.0 0.6 63 12 1963 2013 1988 1956 top-third 2017,2023 48 56.0 56.0 0.0 51 23 1962 2002 1988 1958 top-third 1958,1990,2017 60 55.7 56.0 -0.3 46 27 1963 2003 1988 1958 normal 1956,2011,2012