1991-2020 Degrees Fahrenheit 1 63.6 63.5 0.1 54 21 1950 2007 2017 2015 top-third 2 65.6 64.5 1.1 67 8 1950 2011 2017 2011 top-third 3 64.7 63.3 1.4 70 5 1950 2011 2017 2012 top-tenth 4 62.3 60.5 1.8 73 2 1950 2012 2017 2012 top-tenth 5 58.9 57.0 1.9 73 2 1975 2012 2017 2012 top-tenth 6 54.9 53.3 1.6 72 3 1950,1975 2012 2017 2012 top-tenth 7 51.2 49.2 2.0 73 2 1979 2020 2017 2017 top-tenth 2012,2017 8 47.9 45.2 2.7 74 1 1984 2018 2017 2018 highest 9 45.4 42.2 3.2 72 1 1979 2018 2017 2018 highest 10 44.8 41.0 3.8 72 1 1973 2018 2017 2018 highest 11 44.8 41.3 3.5 72 1 1973,1992 2018 2017 2018 highest 12 45.8 42.5 3.3 72 1 1973,1992 2018 2017 2018 highest 18 48.8 46.1 2.7 72 1 1984 2018 2017 2018 highest 24 45.2 42.5 2.7 70 1 1993 2018 2017 2018 highest 36 44.8 42.4 2.4 68 1 1975 2018 2013 2018 highest 48 -99 42.3 -99 -99 -99 1976 2019,2020 normal 60 -99 42.2 -99 -99 -99 1977 2020 normal