1991-2020 Degrees Fahrenheit 1 41.3 46.1 -4.8 12 65 1960 2012 1950 1949 bottom-third 2 40.3 42.2 -1.9 23 54 1960 1976 1950 1949 bottom-third 3 42.4 39.9 2.5 65 12 1978 1990 1948 1949 top-third 4 41.9 39.6 2.3 65 12 1978 2012 1948 1949 top-third 1991 5 42.7 41.0 1.7 63 13 1977 2012 1950 1949 top-third 6 46.0 43.7 2.3 69 7 1977 2012 1949 1950 top-tenth 1974 7 48.6 47.2 1.4 66 9 1977 2017 1950 1950 top-third 1991,1992 8 52.0 50.6 1.4 66 9 1977 2017 1950 1950 top-third 1986,1992,2022 9 55.1 53.4 1.7 68 7 1977 2017 1950 1950 top-tenth 1972 10 57.2 55.3 1.9 69 6 1977 2017 1950 1950 top-tenth 11 58.0 56.2 1.8 69 6 1977 2017 1950 1950 top-tenth 12 57.6 56.3 1.3 69 6 1977 2012,2017,2020 1950 1950 top-tenth 1974 18 53.7 52.0 1.7 71 4 1978 2017 1950 1950 top-tenth 24 -99 56.2 -99 -99 -99 1978 2017 normal 36 -99 56.2 -99 -99 -99 1979 2018 normal 48 -99 56.2 -99 -99 -99 1980 2020 normal 60 -99 56.1 -99 -99 -99 1981 2020 normal