1991-2020 Degrees Fahrenheit 1 19.4 24.2 -4.8 36 57 1955 2012 1965 1966 normal 2 8.1 17.2 -9.1 9 84 1913 2012 1965 1966 bottom-tenth 3 6.2 13.3 -7.1 22 71 1912 2012 1966 1964 bottom-third 4 6.2 12.8 -6.6 18 72 2014 2012 1965 1966 bottom-third 1949 5 8.6 15.6 -7.0 12 76 1979 2012 1965 1966 bottom-third 6 14.0 20.0 -6.0 10 77 1920 2012 1959 1966 bottom-third 7 19.6 25.0 -5.4 10 75 1920 2012 1959 1966 bottom-third 1956 8 24.9 29.7 -4.8 12 72 1920 2012 1959 1966 bottom-third 9 29.8 33.7 -3.9 14 70 1951 2012 1959 1966 bottom-third 10 33.0 36.4 -3.4 16 66 1951 2012 1966 1964 bottom-third 11 34.2 37.8 -3.6 10 72 1951 2012 1959 1966 bottom-third 12 34.2 37.9 -3.7 6 76 1951 2012 1959 1966 bottom-tenth 1913,1996 18 28.4 31.8 -3.4 11 67 1951 1999 1960 1964 bottom-third 1960 24 34.5 37.8 -3.3 4 73 1952 2017 1952 1964 bottom-tenth 36 -99 37.8 -99 -99 -99 1952 2000 normal 48 -99 37.8 -99 -99 -99 1952 2002 normal 60 -99 37.7 -99 -99 -99 1953 2002 normal