1991-2020 Degrees Fahrenheit 1 54.4 53.2 1.2 54 23 1950 2017 1967 1964 top-third 2 49.5 47.4 2.1 65 12 1950 2012 1967 1948 top-third 1974 3 42.0 42.4 -0.4 36 41 1978 2017 1967 1964 normal 4 37.7 39.2 -1.5 25 52 1978 2017 1966 1967 bottom-third 1972 5 37.3 38.3 -1.0 34 42 1978 2017 1966 1967 normal 2009 6 37.4 39.2 -1.8 20 56 1978 2012 1963 1967 bottom-third 7 39.7 41.5 -1.8 19 57 1978 2017 1963 1967 bottom-third 8 42.4 44.7 -2.3 11 65 1977 2017 1963 1967 bottom-third 1959 9 45.4 47.9 -2.5 8 68 1977 2017 1963 1967 bottom-tenth 1951 10 48.2 50.7 -2.5 7 69 1977 2017 1963 1967 bottom-tenth 1951 11 50.5 52.6 -2.1 8 68 1977 2017 1963 1967 bottom-tenth 1959,1993 12 51.0 53.5 -2.5 5 71 1977 2017 1968 1967 bottom-tenth 18 47.1 48.7 -1.6 14 61 1978 2017 1964 1967 bottom-third 24 51.8 53.4 -1.6 8 67 1978 2017 1964 1967 bottom-third 1959,1969,1980 36 52.4 53.4 -1.0 18 56 1979 2018 1965 1967 bottom-third 1959,1960,1998 48 52.5 53.4 -0.9 19 54 1980 2019,2020 1966 1967 bottom-third 1959,1969 60 52.5 53.4 -0.9 19 53 1981 2020 1967 1967 bottom-third 1967,1969,1986,1996