1991-2020 Degrees Fahrenheit 1 27.6 30.1 -2.5 31 58 1981 2023 2009 2013 normal 2 30.5 33.0 -2.5 37 51 1981 2016 2011 2013 normal 3 34.6 37.0 -2.4 28 60 1981 2002,2016 2009 2013 bottom-third 1962,2001,2009 4 40.1 41.5 -1.4 34 54 1981 2002 2009 2013 normal 1969,1988 5 45.0 46.3 -1.3 37 51 1977 2012,2016 2009 2013 normal 1969,1988 6 49.5 50.7 -1.2 37 51 1977 2016 2009 2013 normal 1939,1978,2004 7 53.5 54.1 -0.6 53 35 1977 2012,2023 2010 2013 normal 2015 8 55.5 55.8 -0.3 56 32 1941 2012,2023 2010 2013 normal 9 55.9 56.1 -0.2 58 30 1941 2023 2010 2013 normal 10 55.2 55.4 -0.2 58 30 1941 2023 2010 2013 normal 1991 11 53.6 53.8 -0.2 56 32 1941 2023 2010 2013 normal 12 51.7 52.0 -0.3 58 30 1968 2023 2010 2013 normal 1947,2008 18 51.6 51.5 0.1 67 20 1941 2013 2010 2013 top-third 1984 24 52.8 52.0 0.8 79 8 1941 2013,2023 2011 2013 top-tenth 2018 36 53.2 51.9 1.3 83 3 1941 2023 2012 2013 top-tenth 48 53.3 51.9 1.4 83 2 1941 2023 2013 2014 top-tenth 60 52.9 51.8 1.1 82 2 1941,1944 2023 2013 2014 top-tenth 2021