1991-2020 Degrees Fahrenheit 1 27.4 29.9 -2.5 36 40 1951 2012 2014 2017 normal 2 17.4 24.5 -7.1 15 61 2019 2016 2011 2017 bottom-third 3 17.3 21.7 -4.4 27 49 1950 1992 2011 2017 normal 4 17.4 21.1 -3.7 29 46 1950 1992 2011 2017 normal 1997 5 20.0 22.9 -2.9 31 44 1979 2000 2011 2017 normal 6 24.1 26.4 -2.3 31 44 1979 2012 2011 2017 normal 1966 7 28.9 30.9 -2.0 32 43 1952 2012 2011 2017 normal 1955 8 33.5 35.5 -2.0 30 45 1952 2012,2016 2011 2017 normal 1955,1975 9 38.1 39.2 -1.1 38 37 1952 2012,2016 2011 2017 normal 10 40.6 41.5 -0.9 36 38 1952 2016 2011 2017 normal 11 41.8 42.5 -0.7 39 35 1952 2016 2011 2017 normal 1977 12 41.8 42.4 -0.6 41 33 1952 2016 2011 2017 normal 1976 18 36.8 37.0 -0.2 50 23 1952 2013 2011 2017 top-third 1987,1993,2004 24 42.3 42.4 -0.1 47 25 1952 2000 2011 2017 normal 1982,1984 36 43.4 42.4 1.0 60 10 1952 2000 2013 2017 top-third 2001,2023 48 43.3 42.4 0.9 60 8 1953 1992 2013 2008 top-third 60 -99 42.4 -99 -99 -99 1954 1992 normal