1991-2020 Degrees Fahrenheit 1 68.4 69.9 -1.5 30 45 1972 2005 1961 1962 normal 2 62.5 65.7 -3.2 18 57 1961 1991 1961 1962 bottom-third 3 57.9 60.7 -2.8 16 59 1961 1991 1961 1962 bottom-third 1990 4 53.0 55.3 -2.3 20 55 1950,1972 1991 1961 1962 bottom-third 1952,1965,1967,1989,1993 5 46.3 50.3 -4.0 8 67 1978 1991 1960 1962 bottom-third 6 41.7 46.6 -4.9 4 71 1978 2012 1958 1962 bottom-tenth 1958 7 39.2 44.6 -5.4 2 73 1978 2012 1963 1962 bottom-tenth 8 39.2 44.4 -5.2 2 72 1978 2012 1963 1962 bottom-tenth 9 40.8 45.5 -4.7 2 72 1978 2012 1963 1962 bottom-tenth 10 42.8 47.5 -4.7 2 72 1978 2012 1963 1962 bottom-tenth 11 45.3 49.7 -4.4 1 73 1963,1977,1978 2017 1963 1962 lowest 1977,1978 12 47.4 51.7 -4.3 2 72 1977 2012,2017 1963 1962 bottom-tenth 18 46.3 50.0 -3.7 2 71 1979 2017 1959 1962 bottom-tenth 1959,1980 24 48.8 51.6 -2.8 7 65 1978 2017 1959 1962 bottom-tenth 36 48.6 51.6 -3.0 3 67 1979 2018 1963 1962 bottom-tenth 48 48.8 51.5 -2.7 5 63 1980 2019,2022 1961 1962 bottom-tenth 1959,1964 60 48.8 51.5 -2.7 3 63 1981 2020 1961 1962 bottom-tenth 1961,1982