1991-2020 Degrees Fahrenheit 1 11.2 18.5 -7.3 9 66 1970 2023 1957 1956 bottom-third 2 18.6 21.9 -3.3 25 49 1971 2016,2023 1956 1954 normal 2009 3 24.5 26.7 -2.2 29 45 1981 2023 1956 1954 normal 1964,2018 4 30.5 31.9 -1.4 33 41 1981 2023 1956 1955 normal 5 35.4 37.5 -2.1 25 49 1977 2016 1956 1955 normal 1979,1989 6 40.3 42.4 -2.1 26 48 1977 2023 1956 1955 normal 1955,1976 7 43.8 46.1 -2.3 18 55 1977 2023 1957 1956 bottom-third 1990 8 46.3 48.4 -2.1 20 52 1981 2023 1957 1956 bottom-third 1988,1990,1996 9 46.7 49.1 -2.4 11 60 1977 2023 1957 1956 bottom-third 10 45.9 48.5 -2.6 8 63 1977 2023 1957 1956 bottom-third 1970 11 43.8 46.8 -3.0 4 67 1977 2023 1957 1956 bottom-tenth 12 42.0 44.6 -2.6 8 62 1968 2023 1957 1956 bottom-third 1970 18 41.4 44.1 -2.7 8 60 1982 2013 1957 1956 bottom-third 1970,1979 24 43.0 44.8 -1.8 20 44 1969 2013 1957 1956 bottom-third 1976,1987,1988,2004 36 43.1 45.0 -1.9 20 39 1970 2013,2023 1957 1956 normal 1980,1983 48 43.7 45.0 -1.3 31 24 1971 2013 1957 1956 normal 1985,1986 60 43.9 45.0 -1.1 31 20 1968,1970,1971,1972 2014 1957 1956 normal 1958