1991-2020 Degrees Fahrenheit 1 43.6 47.0 -3.4 14 69 1976 2015 1996 2011 bottom-third 2 51.2 52.4 -1.2 37 46 1976 1975 2008 2011 normal 3 57.4 58.1 -0.7 49 34 1976 2015 2008 2011 normal 2013 4 62.5 62.7 -0.2 57 26 1940 2015 2008 2011 top-third 5 66.3 65.8 0.5 69 14 1940 2016 2009 2011 top-third 6 67.4 67.0 0.4 68 14 1976 2016,2020 2009 2011 top-third 1999 7 67.4 66.6 0.8 70 12 1967 2015 2009 2011 top-third 8 65.8 65.0 0.8 71 11 1967 2010,2015 2009 2011 top-third 9 64.3 62.6 1.7 77 4 1967 2010 2011 2010 top-tenth 2015 10 61.9 59.9 2.0 79 2 1967 2016 2011 2010 top-tenth 2010,2020 11 59.6 57.4 2.2 79 2 1967 2020 2011 2012 top-tenth 12 58.2 55.9 2.3 79 2 1978,1996 2016 2011 2012 top-tenth 18 61.6 59.5 2.1 77 2 1963 2016 2011 2012 top-tenth 24 57.2 55.8 1.4 72 6 1963 2017 2011 2012 top-tenth 36 57.2 55.8 1.4 70 5 1963 2021,2022 2011 2012 top-tenth 2020 48 56.7 55.7 1.0 64 8 1964,1965 2022 2011 2012 top-third 60 56.6 55.7 0.9 63 6 1965,1967 2020 2011 2012 top-tenth 2013,2017,2018