1991-2020 Degrees Fahrenheit 1 31.6 35.5 -3.9 25 59 1979 2017 2010 2013 bottom-third 2 29.7 34.4 -4.7 16 68 1978 2023 2003 2013 bottom-third 3 32.5 35.7 -3.2 27 57 1977 2016 2011 2013 bottom-third 1944,2011 4 35.6 38.5 -2.9 22 61 1977 2016 2003 2013 bottom-third 1942,1987 5 40.5 42.3 -1.8 37 46 1977 2016 2004 2013 normal 1942 6 45.0 46.8 -1.8 35 48 1977 2016 2003 2013 normal 2015 7 49.1 51.1 -2.0 31 52 1977 2016 2003 2013 normal 1942,1980,1989,2015 8 53.0 54.4 -1.4 43 40 1977 2016 2003 2013 normal 1984 9 55.3 56.5 -1.2 48 34 1977 2016 2010 2013 normal 1955,1983 10 56.2 57.2 -1.0 49 33 1977 2016 2010 2013 normal 1956,1983 11 56.0 56.9 -0.9 50 32 1977 2016 2010 2013 normal 1952,1975,1998,2010 12 54.7 55.8 -1.1 46 35 1968 2017 2004 2013 normal 2003 18 52.3 52.8 -0.5 57 23 1978 2017 2010 2013 top-third 1953,1991 24 56.2 55.7 0.5 65 13 1945,1964,1968,1969,1978 2017 2011 2013 top-third 2000 36 56.8 55.7 1.1 66 9 1963,1970 2018 2012 2013 top-third 48 56.9 55.6 1.3 65 7 1964,1970 2023 2013 2013 top-tenth 2013 60 56.5 55.6 0.9 60 9 1970 2020 2012 2013 top-third 2018