1991-2020 Degrees Fahrenheit 1 41.7 46.0 -4.3 13 64 1960 2012 1975 1980 bottom-third 2018 2 39.6 42.1 -2.5 18 59 1960 1976 1980 1977 bottom-third 1964,1972 3 35.8 39.8 -4.0 14 63 1978 1990 1980 1976 bottom-third 2010 4 36.0 39.5 -3.5 17 60 1978 2012 1978 1980 bottom-third 5 37.5 40.9 -3.4 12 64 1977 2012 1978 1980 bottom-third 1969 6 40.2 43.6 -3.4 9 67 1977 2012 1978 1980 bottom-third 7 44.5 47.1 -2.6 12 63 1977 2017 1978 1980 bottom-third 8 48.5 50.6 -2.1 15 60 1977 2017 1978 1980 bottom-third 1959 9 51.7 53.3 -1.6 20 55 1977 2017 1980 1979 bottom-third 10 53.4 55.2 -1.8 16 59 1977 2017 1980 1979 bottom-third 1959,1966 11 54.4 56.1 -1.7 18 57 1977 2017 1980 1979 bottom-third 12 54.3 56.2 -1.9 10 65 1977 2012,2017,2020 1980 1979 bottom-third 1959,1962,1969,1984,2015 18 50.0 51.9 -1.9 13 62 1978 2017 1980 1976 bottom-third 1962 24 54.2 56.1 -1.9 8 66 1978 2017 1978 1980 bottom-third 36 54.6 56.1 -1.5 13 60 1979 2018 1980 1976 bottom-third 1971 48 54.4 56.1 -1.7 9 63 1980 2020 1980 1977 bottom-third 1969 60 53.8 56.0 -2.2 1 70 1981 2020 1981 1980 lowest