1991-2020 Degrees Fahrenheit 1 29.5 38.2 -8.7 3 60 1989 2015 1963 1962 bottom-tenth 2 39.1 42.3 -3.2 8 52 1989 2015 1963 1963 bottom-third 1983 3 45.6 47.2 -1.6 20 40 1976 2015 1963 1963 bottom-third 4 50.2 52.7 -2.5 9 51 1976 2015 1963 1963 bottom-third 1972 5 54.7 57.4 -2.7 9 51 1976 2021 1963 1963 bottom-third 6 58.1 60.8 -2.7 8 52 1976 2021 1963 1963 bottom-third 7 60.0 62.6 -2.6 9 51 1976 2021 1963 1963 bottom-third 1966 8 60.2 62.8 -2.6 6 54 1976 2015 1963 1963 bottom-tenth 1966,1989 9 59.6 62.0 -2.4 8 52 1976 2015 1963 1963 bottom-third 10 58.2 60.2 -2.0 10 50 1976 2021 1963 1963 bottom-third 11 55.4 58.1 -2.7 4 56 1967 2012 1963 1963 bottom-tenth 12 53.2 56.1 -2.9 2 58 1966 2012 1963 1963 bottom-tenth 18 -99 57.7 -99 -99 -99 1967,1977 2012 normal 24 -99 56.1 -99 -99 -99 1967 2021 normal 36 -99 56.1 -99 -99 -99 1968 2021 normal 48 -99 56.1 -99 -99 -99 1969 2020,2021,2022 normal 60 -99 56.1 -99 -99 -99 1970 2021 normal