1991-2020 Degrees Fahrenheit 1 46.3 47.7 -1.4 34 41 1977 1950 1970 1972 normal 2 50.5 48.9 1.6 58 17 1977 1950 1971 1972 top-third 2007 3 51.7 51.2 0.5 48 26 1977 1974 1971 1972 normal 1975 4 55.2 54.8 0.4 48 26 1977 2017 1971 1972 normal 5 59.5 59.1 0.4 52 22 1977 2017 1970 1972 top-third 2008 6 62.9 62.9 0.0 50 24 1977 2017 1970 1972 top-third 2000,2007 7 65.2 65.7 -0.5 42 32 1977 2017 1970 1972 normal 2009 8 66.5 67.4 -0.9 29 45 1977 2017 1970 1972 normal 1965,1980,1994 9 66.8 68.0 -1.2 18 56 1977 2017 1970 1972 bottom-third 1975,1984,2004,2010 10 66.6 67.6 -1.0 22 52 1977 2017 1970 1972 bottom-third 1961,2015 11 65.6 66.7 -1.1 22 52 1977 2017 1970 1972 bottom-third 12 64.1 65.4 -1.3 16 58 1977 2017 1970 1972 bottom-third 1959 18 64.4 64.5 -0.1 47 25 1969 2017,2020 1972 1972 normal 1957,1972,1986,2003 24 64.6 65.4 -0.8 29 43 1970 2020 1971 1972 normal 1979 36 64.7 65.3 -0.6 30 40 1970 2019,2021 1972 1960 normal 1997 48 64.2 65.3 -1.1 13 55 1970 2020 1972 1965 bottom-third 1965,1984 60 64.0 65.2 -1.2 7 59 1970 2020,2021 1972 1967 bottom-tenth 1965,1967,1979,1981