1991-2020 Degrees Fahrenheit 1 36.1 37.7 -1.6 38 47 1979 2017 2010 2012 normal 2 37.1 36.6 0.5 60 25 1978 2023 2011 2012 top-third 1992 3 39.3 37.6 1.7 71 14 1963 2023 2011 2012 top-third 1975,1997,2022 4 40.5 40.2 0.3 55 29 1977 2002,2012 2011 2012 normal 5 44.3 43.9 0.4 60 24 1977 2017 2011 2012 top-third 1954,1975,1983 6 48.7 48.3 0.4 64 20 1977 2017 2011 2012 top-third 1971,2019 7 52.9 52.4 0.5 65 19 1977 2017 2011 2012 top-third 8 56.6 55.8 0.8 71 13 1977 2017 2011 2012 top-third 9 58.6 57.9 0.7 70 13 1977 2017 2011 2012 top-third 1974 10 59.8 58.6 1.2 75 8 1977 2012 2011 2012 top-tenth 1992 11 59.5 58.4 1.1 75 8 1977 2012 2011 2012 top-tenth 12 59.1 57.3 1.8 80 3 1977 2012 2011 2012 top-tenth 2020 18 56.4 54.3 2.1 80 2 1941 2017 2012 2013 top-tenth 24 59.3 57.3 2.0 80 1 1964 2013 2012 2013 highest 36 59.1 57.3 1.8 78 1 1963 2013 2012 2013 highest 48 58.3 57.3 1.0 74 3 1964 2023 2012 2013 top-tenth 2014,2022 60 58.0 57.2 0.8 70 5 1965 2020,2023 2012 2013 top-tenth