1925-2000 Degrees Fahrenheit 1 15.0 10.8 4.2 77 23 1959 2019 1931 1926 top-third 2 4.9 7.8 -2.9 22 78 1972 2019 1930 1931 bottom-third 3 1.1 5.9 -4.8 10 90 1971 2016 1925 1931 bottom-tenth 4 2.0 5.4 -3.4 14 85 1971 2016 1932 1931 bottom-third 1965 5 4.8 6.6 -1.8 24 75 1956 2016 1932 1931 bottom-third 6 8.0 9.8 -1.8 24 75 1956 2019 1932 1931 bottom-third 7 12.6 14.2 -1.6 23 76 1971 2019 1932 1931 bottom-third 1965 8 17.2 18.6 -1.4 24 75 1971 2019 1932 1931 bottom-third 1965,1999 9 21.0 22.4 -1.4 18 81 1971 2019 1932 1931 bottom-third 1936,2012 10 23.7 25.1 -1.4 18 81 1971 2019 1932 1931 bottom-third 11 24.8 26.2 -1.4 16 83 1956 2019 1932 1931 bottom-third 1936 12 24.6 26.0 -1.4 16 83 1956 2016 1928 1931 bottom-third 1928,1964 18 20.5 20.6 -0.1 32 66 1972 2019 1928 1931 bottom-third 1964,1983,2000 24 25.7 26.0 -0.3 23 75 1972 2019 1932 1931 bottom-third 1955,1960,1977,2013 36 25.9 26.0 -0.1 32 65 1973 2018 1932 1931 bottom-third 1963 48 26.2 25.9 0.3 37 59 1974 2019 1931 1931 normal 1931,1970,1985 60 25.9 25.9 0.0 35 60 1975 2019 1932 1931 normal 1947,1961