1991-2020 Degrees Fahrenheit 1 61.2 60.0 1.2 68 10 1964 1997 2015 2014 top-third 2 60.8 58.8 2.0 74 4 1964 1992 2015 2014 top-tenth 1987 3 59.8 57.8 2.0 73 5 1948 1992 2015 2014 top-tenth 4 59.1 56.8 2.3 75 2 1948 1992 2015 1992 top-tenth 5 57.9 55.7 2.2 76 1 1949 2014,2015,2016 2015 2015 highest 2014,2015 6 56.7 55.0 1.7 75 2 1949 2015 2014 2015 top-tenth 1992 7 56.3 55.2 1.1 70 7 1949 2015 2013 2015 top-tenth 8 57.5 56.2 1.3 73 4 1949 2015 2014 2015 top-tenth 2020 9 58.6 57.2 1.4 73 4 1949 2015 2014 2015 top-tenth 2018 10 59.5 58.0 1.5 74 3 1949 2015 2014 2015 top-tenth 11 60.2 58.6 1.6 74 2 1949 2015 2014 2015 top-tenth 2020 12 60.4 58.9 1.5 72 3 1949 2015 2014 2015 top-tenth 18 59.5 57.6 1.9 73 1 1949,1950 2015,2016 2015 2015 highest 2015 24 60.7 58.8 1.9 72 1 1950 2016 2015 2016 highest 36 60.3 58.8 1.5 70 1 1950 2016 2015 2016 highest 48 59.8 58.8 1.0 66 3 1951,1952,1955,1956 2018 2015 2016 top-tenth 60 59.4 58.7 0.7 65 3 1952,1953,1956 2018 2015 2016 top-tenth