1991-2020 Degrees Fahrenheit 1 60.1 65.3 -5.2 7 87 1973 2011 1973 1976 bottom-tenth 2 56.7 61.1 -4.4 11 83 1958 2011 1973 1976 bottom-third 3 54.0 57.2 -3.2 21 73 1958 2017 1975 1976 bottom-third 1966,1980,2010 4 50.3 54.0 -3.7 9 83 1958 2017 1973 1976 bottom-tenth 1942,1970 5 48.8 52.3 -3.5 10 82 1973 2017 1973 1976 bottom-third 6 48.2 52.4 -4.2 3 89 1973 2017 1973 1976 bottom-tenth 7 49.4 54.3 -4.9 1 91 1977 2017 1977 1976 lowest 8 52.0 56.9 -4.9 1 91 1977 2017 1977 1976 lowest 9 54.8 59.7 -4.9 1 91 1977 2017 1977 1976 lowest 10 56.8 62.1 -5.3 1 91 1977 2017 1977 1976 lowest 11 58.6 63.8 -5.2 1 91 1977 2017 1977 1976 lowest 12 59.3 64.7 -5.4 1 90 1977 2017 1977 1976 lowest 18 56.9 60.6 -3.7 1 89 1977 2017 1977 1976 lowest 24 60.8 64.7 -3.9 1 88 1977 2000 1977 1976 lowest 36 61.3 64.6 -3.3 1 86 1977 2018 1977 1976 lowest 48 61.9 64.6 -2.7 1 84 1977 2019,2020 1977 1976 lowest 60 61.7 64.5 -2.8 1 82 1977 2020 1977 1976 lowest