1991-2020 Degrees Fahrenheit 1 37.3 42.1 -4.8 16 64 1977 1950 1968 1967 bottom-third 2 38.1 43.5 -5.4 10 70 1977 1972,2016 1963 1968 bottom-third 3 42.1 46.3 -4.2 11 69 1977 2016 1963 1968 bottom-third 4 46.9 50.2 -3.3 12 68 1977 2016 1968 1967 bottom-third 1946 5 51.6 54.7 -3.1 12 68 1977 2016 1968 1967 bottom-third 1981 6 56.4 58.8 -2.4 18 62 1977 2008 1968 1967 bottom-third 1981 7 59.5 61.9 -2.4 15 65 1977 2017 1968 1967 bottom-third 1946,1956 8 61.4 63.8 -2.4 18 62 1977 2012,2017 1968 1967 bottom-third 1958,1967,1981 9 61.7 64.4 -2.7 10 69 1977 2012 1968 1967 bottom-third 10 61.5 64.0 -2.5 11 68 1977 2012 1968 1966 bottom-third 1961 11 60.6 63.0 -2.4 15 64 1968,1977 2017 1968 1965 bottom-third 12 58.6 61.5 -2.9 11 68 1948,1968 2012 1968 1967 bottom-third 1979 18 57.2 60.5 -3.3 2 77 1964 2017 1968 1968 bottom-tenth 1968,1978 24 58.0 61.4 -3.4 1 77 1969 2013 1969 1968 lowest 36 58.3 61.4 -3.1 2 75 1970 2013,2018,2019 1969 1968 bottom-tenth 48 58.5 61.4 -2.9 3 73 1970 2020 1964 1968 bottom-tenth 1971 60 58.6 61.3 -2.7 4 71 1970 2020,2021 1968 1967 bottom-tenth 1971