1991-2020 Degrees Fahrenheit 1 68.5 66.4 2.1 58 11 1973 2004 2006 2004 top-third 2 64.3 63.3 1.0 56 13 1964 2015 2006 2004 top-third 1989 3 60.4 61.2 -0.8 39 28 1955 2015 2006 2004 normal 1959,1999 4 58.9 59.7 -0.8 34 29 1973 2015 2006 2005 normal 2005,2011 5 60.3 60.6 -0.3 41 22 1973 2015 2006 2004 normal 1982 6 62.6 63.3 -0.7 36 26 1973 2015 2005 2006 normal 1994 7 66.0 66.9 -0.9 33 29 1973 2015 2005 2006 normal 1967,1982,1995 8 69.4 70.3 -0.9 28 34 1973 2015 2005 2006 normal 1967 9 72.5 72.9 -0.4 40 22 1973 2015 2006 2006 normal 1984,2006,2011,2019 10 74.5 74.5 0.0 45 17 1973 2015 2006 2004 top-third 1959 11 75.2 75.0 0.2 48 14 1973 2015 2006 2004 top-third 2003 12 74.8 74.8 0.0 47 15 1973 2015 2006 2004 top-third 2019 18 70.8 71.0 -0.2 41 16 1973 2015,2018 2006 2004 top-third 1990,2023 24 74.5 74.8 -0.3 40 17 1973 2015 2006 2005 top-third 1960,2005,2020 36 74.3 74.9 -0.6 31 21 1974 2017 1995 2006 normal 48 74.5 74.8 -0.3 30 17 1975,1976 2018 1996 2006 normal 1996 60 74.6 74.8 -0.2 29 13 1976,1977 2018 2006 2006 top-third 2005,2006