1925-2000 Degrees Fahrenheit 1 9.2 2.2 7.0 77 23 2012 1981 1939 1937 top-third 2 9.0 3.0 6.0 80 19 1934 2001 1939 1931 top-third 1926 3 7.5 5.9 1.6 61 38 1943 2001 1938 1939 normal 1998 4 11.4 10.8 0.6 48 51 1934 2003 1936 1939 normal 5 17.0 16.7 0.3 45 54 1934 2003 1936 1939 normal 1996 6 22.1 22.2 -0.1 41 58 1934 2003 1936 1939 normal 1952 7 26.4 26.6 -0.2 38 61 1934 2003 1936 1939 normal 8 29.2 29.4 -0.2 36 63 1934 2003 1936 1939 normal 1991,2013 9 29.9 30.3 -0.4 32 67 1934 2003 1936 1939 bottom-third 1973 10 29.4 29.6 -0.2 37 62 1956 2018 1936 1939 normal 11 27.4 27.9 -0.5 32 67 1956 2016 1936 1939 bottom-third 1936 12 25.7 26.0 -0.3 37 62 1956 2020 1938 1939 normal 1964 18 25.3 24.7 0.6 58 40 1957,1972 2020 1937 1939 normal 1931,1936,1937,1985,1996 24 26.3 26.0 0.3 42 56 1957 2017 1939 1939 normal 1931,1939,1984,2009 36 26.1 25.9 0.2 36 61 1957 2017,2018 1936 1939 normal 1997 48 26.4 25.9 0.5 42 54 1975 2020 1939 1939 normal 1939,1993 60 26.3 25.9 0.4 41 54 1976 2020 1938 1939 normal 1948,1986,1987,2013