1991-2020 Degrees Fahrenheit 1 54.3 57.7 -3.4 17 59 1960 2012 1971 1977 bottom-third 2 48.3 54.5 -6.2 4 72 1960 2023 1960 1977 bottom-tenth 3 45.6 52.2 -6.6 1 74 1978 2017 1978 1977 lowest 4 45.9 51.7 -5.8 1 74 1978 2017 1978 1977 lowest 5 48.4 52.5 -4.1 5 69 1977 2017 1977 1976 bottom-tenth 1964 6 50.6 54.7 -4.1 2 72 1977 2017 1977 1976 bottom-tenth 7 54.5 57.8 -3.3 5 69 1977 2017 1977 1976 bottom-tenth 1964 8 57.8 60.8 -3.0 5 69 1977 2017 1977 1976 bottom-tenth 2010 9 60.6 63.2 -2.6 8 66 1968 2017 1977 1976 bottom-third 1966 10 62.7 64.8 -2.1 9 65 1968 2017 1977 1976 bottom-third 11 63.7 65.5 -1.8 11 63 1968,1977 2017 1977 1976 bottom-third 1998 12 64.0 65.4 -1.4 13 61 1977 2017 1977 1976 bottom-third 1984 18 59.2 61.8 -2.6 2 70 1970 2017 1970 1977 bottom-tenth 1969 24 62.9 65.4 -2.5 2 70 1969 2017 1969 1977 bottom-tenth 36 63.4 65.3 -1.9 3 67 1970 2018 1970 1977 bottom-tenth 1968 48 63.6 65.3 -1.7 4 64 1970,1971 2020 1971 1977 bottom-tenth 1980 60 64.2 65.3 -1.1 11 55 1970 2020 1973 1977 bottom-third 1964,1965,1973