1991-2020 Degrees Fahrenheit 1 38.8 38.2 0.6 46 31 1978 1976 1950 1949 normal 2 42.4 36.6 5.8 72 5 1978 2017 1948 1949 top-tenth 3 41.6 37.4 4.2 73 4 1977 2017 1948 1949 top-tenth 4 42.5 39.6 2.9 69 7 1977 2017 1950 1949 top-tenth 5 46.4 43.1 3.3 74 2 1977 2017 1949 1950 top-tenth 6 49.3 47.3 2.0 70 5 1977 2017 1950 1950 top-tenth 7 53.0 51.2 1.8 69 6 1977 2017 1950 1950 top-tenth 1974 8 56.3 54.3 2.0 72 3 1977 2017 1950 1950 top-tenth 9 58.4 56.3 2.1 73 2 1977 2017 1950 1950 top-tenth 2020 10 59.2 57.1 2.1 72 3 1977 2017 1950 1950 top-tenth 11 58.6 57.1 1.5 69 6 1977 2017 1950 1950 top-tenth 12 57.4 56.2 1.2 68 7 1977 2017 1950 1950 top-tenth 1974 18 -99 53.2 -99 -99 -99 1978 2017 normal 24 -99 56.1 -99 -99 -99 1978 2017 normal 36 -99 56.1 -99 -99 -99 1979 2018 normal 48 -99 56.1 -99 -99 -99 1980 2020 normal 60 -99 56.0 -99 -99 -99 1981 2020 normal