1991-2020 Degrees Fahrenheit 1 51.1 45.3 5.8 75 3 1960 2012 2015 2012 top-tenth 2 46.0 39.9 6.1 75 3 1960 2012 2015 2012 top-tenth 3 41.0 36.6 4.4 74 4 1979 2012 2015 2012 top-tenth 4 40.7 35.8 4.9 76 2 1979 2012 2015 2012 top-tenth 1992 5 42.3 37.4 4.9 76 2 1979 2012 2015 2012 top-tenth 6 45.0 40.6 4.4 75 3 1979 2012 2015 2012 top-tenth 7 49.1 44.7 4.4 77 1 1979 2016 2015 2016 highest 8 52.3 48.8 3.5 75 3 1979 2012,2017 2015 2012 top-tenth 9 55.3 52.2 3.1 74 3 1979 2012 2015 2012 top-tenth 10 57.5 54.5 3.0 74 3 1962,1979 2012 2015 2012 top-tenth 11 58.1 55.5 2.6 74 3 1962 2012 2015 2012 top-tenth 12 58.0 55.5 2.5 74 3 1962 2012 2015 2012 top-tenth 18 51.9 50.5 1.4 69 8 1979 2017 2015 2013 top-tenth 24 56.6 55.4 1.2 69 7 1979 2017 2015 2013 top-tenth 2007 36 55.5 55.4 0.1 54 21 1979 2018 2015 2014 top-third 2009 48 56.0 55.4 0.6 63 11 1980 2018,2019 2012 2015 top-third 60 56.5 55.4 1.1 71 2 1962 2020 2015 2016 top-tenth 2017,2019