1991-2020 Degrees Fahrenheit 1 37.1 32.6 4.5 70 7 1977 2023 2005 2006 top-tenth 2 39.4 34.9 4.5 73 3 1961 2002 2006 2002 top-tenth 3 42.8 38.7 4.1 73 3 1977 2002 2006 2002 top-tenth 4 45.9 43.4 2.5 72 4 1977 2002 2006 2002 top-tenth 5 49.8 48.7 1.1 65 10 1977 2016 2005 2006 top-third 2008 6 54.3 53.2 1.1 65 10 1977 2016 2005 2006 top-third 7 57.8 56.7 1.1 65 10 1977 2017 2005 2006 top-third 8 59.7 58.8 0.9 65 10 1977 2017 2005 2006 top-third 9 60.0 59.4 0.6 62 13 1977 2016 2005 2006 top-third 10 59.6 58.9 0.7 65 10 1977 2016 2005 2006 top-third 2021 11 58.3 57.5 0.8 66 9 1977 2017 2006 2007 top-third 12 56.4 55.6 0.8 67 8 1968 2013 2006 2007 top-third 18 55.8 54.7 1.1 67 6 1964,1968 2017 2006 2007 top-tenth 24 56.2 55.5 0.7 65 8 1964 2013 2006 2007 top-third 2020 36 56.0 55.5 0.5 63 8 1963 2023 2006 2007 top-third 2020 48 55.4 55.5 -0.1 56 13 1964 2023 2006 2007 top-third 60 55.3 55.5 -0.2 53 14 1965 2023 2006 2006 top-third 2006,2008,2011