1991-2020 Degrees Fahrenheit 1 37.9 34.8 3.1 61 17 1979 2017 1951 1952 top-third 2 34.6 32.5 2.1 62 16 1979 1992 1951 1952 top-third 3 32.7 32.8 -0.1 55 23 1979 1992 1951 1952 top-third 2009 4 33.9 35.6 -1.7 38 40 1979 2000 1951 1950 normal 5 38.2 39.9 -1.7 32 46 1979 2017 1949 1951 normal 1974 6 42.5 44.8 -2.3 26 52 1979 2017 1949 1951 bottom-third 2014 7 47.4 49.5 -2.1 25 53 1979 2017 1951 1950 bottom-third 1967,2014 8 51.0 53.3 -2.3 20 57 1979 2017 1951 1950 bottom-third 1959,1970,1971 9 52.9 55.7 -2.8 12 65 1979 2017 1951 1950 bottom-third 1969,1994,1997 10 54.0 56.7 -2.7 12 65 1977 2017 1951 1950 bottom-third 1982 11 53.6 56.6 -3.0 9 68 1962 2017 1951 1950 bottom-third 1994 12 52.3 55.7 -3.4 5 72 1962 2013 1951 1950 bottom-tenth 18 49.2 52.0 -2.8 10 67 1979 2017 1952 1951 bottom-third 1959 24 52.2 55.6 -3.4 3 73 1962,1963 2013 1952 1951 bottom-tenth 1980 36 52.9 55.6 -2.7 6 69 1979 2013 1952 1951 bottom-tenth 48 53.0 55.6 -2.6 6 68 1962,1980 2019 1952 1951 bottom-tenth 1961,1970 60 53.1 55.6 -2.5 4 69 1963 2017,2020 1952 1952 bottom-tenth 1971,1979,1981