1991-2020 Degrees Fahrenheit 1 27.2 24.2 3.0 77 16 1955 2012 1967 1961 top-third 2 15.9 17.2 -1.3 57 36 1913 2012 1967 1961 normal 3 11.6 13.3 -1.7 58 35 1912 2012 1967 1961 normal 4 10.8 12.8 -2.0 55 35 2014 2012 1967 1961 normal 1991 5 13.0 15.6 -2.6 48 40 1979 2012 1967 1964 normal 1964,1990 6 17.6 20.0 -2.4 41 46 1920 2012 1967 1964 normal 2018 7 23.0 25.0 -2.0 44 41 1920 2012 1967 1964 normal 1976 8 27.8 29.7 -1.9 40 44 1920 2012 1967 1964 normal 1975,2013,2018 9 31.8 33.7 -1.9 40 44 1951 2012 1967 1964 normal 2018 10 34.6 36.4 -1.8 35 47 1951 2012 1967 1964 normal 1985,2019 11 35.5 37.8 -2.3 25 57 1951 2012 1967 1964 bottom-third 1949,1963,1969,1977 12 35.5 37.9 -2.4 23 59 1951 2012 1967 1964 bottom-third 1971 18 28.3 31.8 -3.5 10 68 1951 1999 1957 1967 bottom-third 24 34.8 37.8 -3.0 7 70 1952 2017 1967 1964 bottom-tenth 1997 36 34.8 37.8 -3.0 4 68 1952 2000 1953 1964 bottom-tenth 48 -99 37.8 -99 -99 -99 1952 2002 normal 60 -99 37.7 -99 -99 -99 1953 2002 normal