1991-2020 Degrees Fahrenheit 1 21.4 22.0 -0.6 50 36 1983 2015 1951 1952 normal 2 30.1 28.4 1.7 69 17 1985 2001 1952 1941 top-third 2004 3 39.2 35.5 3.7 81 5 1985 2015 1952 1953 top-tenth 4 45.0 42.5 2.5 78 8 1985 2015 1952 1953 top-tenth 5 50.7 48.4 2.3 79 7 1985 2015 1952 1953 top-tenth 6 54.5 52.7 1.8 78 8 1985 2011 1952 1953 top-tenth 7 56.9 55.1 1.8 80 6 1985 2021 1952 1953 top-tenth 8 57.2 55.7 1.5 77 9 1945 2021 1952 1941 top-tenth 9 55.4 54.7 0.7 67 19 1945 2021 1952 1949 top-third 1963,1994 10 53.0 52.6 0.4 64 21 1951 2021 1952 1949 top-third 2017 11 49.8 49.7 0.1 66 19 1951 2012 1952 1941 top-third 1954,1963,1990,1994 12 47.0 46.9 0.1 65 20 1950 2012 1952 1941 top-third 1964,2002 18 48.5 48.8 -0.3 57 28 1951 2012 1952 1949 top-third 2018 24 46.5 46.9 -0.4 60 24 1951 1999,2012,2017 1952 1942 top-third 1964,1974,2020 36 45.0 46.9 -1.9 14 69 1952 2012,2017 1952 1949 bottom-third 1997 48 44.3 46.9 -2.6 5 77 1972 2018 1952 1950 bottom-tenth 60 44.7 46.9 -2.2 6 75 1969,1972 2002 1952 1950 bottom-tenth 1954,1971