1991-2020 Degrees Fahrenheit 1 90.8 88.7 2.1 56 12 1965 2021 2015 2016 top-third 2 85.3 84.3 1.0 55 13 1965 2001,2006 2016 2016 top-third 1960,2016 3 82.0 80.3 1.7 61 7 1967,1975 2000 2016 2013 top-tenth 1989 4 79.1 76.8 2.3 65 3 1975 2004 2016 2013 top-tenth 5 75.8 73.5 2.3 67 1 1975 2014,2015,2016,2017 2016 2016 highest 2014,2015,2016 6 72.5 70.8 1.7 63 3 1975 2014 2016 2015 top-tenth 1996 7 70.3 68.7 1.6 58 4 1975 2015 2016 2015 top-tenth 8 69.8 68.1 1.7 57 5 1975 1996 2016 2015 top-tenth 2000 9 70.9 69.1 1.8 58 3 1975 1996,2015 2016 2015 top-tenth 2018 10 72.4 71.0 1.4 57 4 1973 1996 2016 2015 top-tenth 11 74.4 73.1 1.3 55 6 1973 1996 2014 2016 top-tenth 12 76.2 74.9 1.3 57 4 1975 1996 2016 2015 top-tenth 18 74.9 73.5 1.4 57 3 1976 2015 2016 2016 top-tenth 2016 24 76.1 74.9 1.2 53 3 1973,1975,1976 2018 2015 2016 top-tenth 1997 36 76.2 74.9 1.3 50 1 1975,1977 2017,2018 2016 2017 highest 2018 48 76.0 74.9 1.1 44 2 1975,1976 2018 2016 2017 top-tenth 60 75.9 74.8 1.1 39 2 1977 2018 2016 2017 top-tenth