1991-2020 Degrees Fahrenheit 1 31.6 32.6 -1.0 45 32 1977 2023 2015 2013 normal 2 39.5 34.9 4.6 74 2 1961 2002 2015 2002 top-tenth 3 43.5 38.7 4.8 74 2 1977 2002 2015 2002 top-tenth 4 46.7 43.4 3.3 74 2 1977 2002 2015 2002 top-tenth 5 51.7 48.7 3.0 74 1 1977 2016 2015 2016 highest 6 55.7 53.2 2.5 74 1 1977 2016 2015 2016 highest 7 58.7 56.7 2.0 73 2 1977 2017 2015 2016 top-tenth 8 60.5 58.8 1.7 73 2 1977 2017 2015 2016 top-tenth 2021 9 61.5 59.4 2.1 74 1 1977 2016 2015 2016 highest 10 60.8 58.9 1.9 74 1 1977 2016 2015 2016 highest 11 58.7 57.5 1.2 70 5 1977 2017 2015 2013 top-tenth 2021 12 55.8 55.6 0.2 62 13 1968 2013 2015 2013 top-third 2011 18 54.3 54.7 -0.4 57 16 1964,1968 2017 2015 2013 top-third 1991,2005,2009 24 54.5 55.5 -1.0 52 21 1964 2013 2015 2014 top-third 1947,1955,2005 36 54.4 55.5 -1.1 49 22 1963 2023 1990 2015 top-third 1956 48 55.2 55.5 -0.3 55 14 1964 2023 2011 2015 top-third 2010,2017 60 55.5 55.5 0.0 58 9 1965 2023 2015 2015 top-third 2009,2015