1991-2020 Degrees Fahrenheit 1 24.4 33.4 -9.0 8 78 1965 2012 1940 1939 bottom-tenth 2 21.9 27.0 -5.1 25 61 1965 2012 1939 1940 bottom-third 1969 3 16.6 23.4 -6.8 12 74 1979 2012 1940 1939 bottom-third 4 19.2 23.0 -3.8 26 60 2014 2012 1940 1939 bottom-third 1959,2011 5 22.8 25.4 -2.6 37 49 1951 2012 1939 1940 normal 1974 6 27.0 29.4 -2.4 30 56 2014 2012 1940 1939 normal 1949,1955,2008 7 32.3 34.3 -2.0 34 52 1978 2012 1940 1939 normal 1985,2011 8 37.2 39.0 -1.8 34 52 1978 2012 1940 1939 normal 1941,1948 9 41.5 42.9 -1.4 40 46 1978 2012 1940 1939 normal 1985 10 44.2 45.6 -1.4 38 48 1978 2012 1940 1939 normal 2015 11 46.1 46.9 -0.8 47 39 1951 2012 1939 1940 normal 1944 12 45.8 46.9 -1.1 43 43 1951 2012 1940 1939 normal 1950,1960 18 39.7 41.1 -1.4 35 50 1952 2017 1940 1940 normal 1943,1947,1960 24 46.0 46.9 -0.9 44 41 1952 2017 1940 1940 normal 36 -99 46.9 -99 -99 -99 1952 2018 normal 48 -99 46.9 -99 -99 -99 1952,1953,1968,1969,1970,1972 2013,2019 normal 60 -99 46.9 -99 -99 -99 1952,1970 2020 normal