1991-2020 Degrees Fahrenheit 1 22.5 19.2 3.3 53 23 2019 1954 1989 1987 top-third 2 23.2 17.6 5.6 66 10 1950,1979 1992 1989 1987 top-third 3 19.3 18.2 1.1 51 24 1950,1979 1992 1989 1987 top-third 4 22.1 21.1 1.0 50 25 1979 2000 1989 1988 top-third 5 26.7 25.6 1.1 55 20 1979 2000 1989 1988 top-third 1953,2013 6 31.8 31.0 0.8 51 24 1979 2016 1989 1988 top-third 1991 7 37.1 36.3 0.8 54 21 1952,1978 2016 1989 1987 top-third 1961 8 41.7 40.4 1.3 58 17 1952,1979 2016 1989 1983 top-third 9 43.8 42.8 1.0 56 18 1952 2016 1989 1988 top-third 1983,1988 10 44.9 43.7 1.2 55 19 1952 2016,2022 1987 1989 top-third 11 44.6 43.5 1.1 55 19 1952 2016 1987 1989 top-third 1995 12 43.0 42.4 0.6 51 23 1952 2016 1986 1989 top-third 18 38.3 38.6 -0.3 46 27 1952 2013 1987 1989 normal 24 43.6 42.4 1.2 59 13 1952 2022 1987 1989 top-third 36 43.8 42.4 1.4 65 5 1952 2000 1988 1989 top-tenth 1992,2022 48 43.8 42.4 1.4 66 2 1953 1992 1989 1990 top-tenth 2008 60 43.2 42.4 0.8 61 5 1954 1992 1989 1990 top-tenth 1993,2009