1991-2020 Degrees Fahrenheit 1 20.4 27.9 -7.5 5 71 2014 2012 1950 1949 bottom-tenth 2 16.9 23.5 -6.6 5 70 2015 2012 1950 1949 bottom-tenth 3 18.5 21.2 -2.7 21 53 2015 2012 1950 1949 bottom-third 1992 4 19.6 21.8 -2.2 31 42 1971 2016 1950 1949 normal 1960 5 21.5 24.3 -2.8 22 51 1959,1971 2012 1950 1949 bottom-third 2001 6 26.0 27.8 -1.8 38 35 1959 2012 1950 1949 normal 1962,1988,2011 7 30.0 32.1 -2.1 30 43 1959 2012 1950 1949 normal 1964,1988 8 34.3 36.2 -1.9 34 39 1959 2012 1950 1949 normal 9 38.2 39.6 -1.4 38 34 1959 2012 1950 1949 normal 1989,2004 10 40.9 41.8 -0.9 45 26 1959 2012 1950 1949 normal 1960,1980 11 42.0 42.9 -0.9 43 27 1959 2012 1950 1950 normal 1980 12 42.0 42.7 -0.7 45 25 1959 2012 1950 1950 normal 18 37.7 37.9 -0.2 50 17 1971,1982 2013 1950 1950 top-third 24 -99 42.9 -99 -99 -99 1968 2013 normal 36 -99 43.0 -99 -99 -99 1965,1968,1970 2018,2023 normal 48 -99 43.0 -99 -99 -99 1968,1970,1971 2013 normal 60 -99 43.1 -99 -99 -99 1971 2013 normal