1991-2020 Degrees Fahrenheit 1 38.5 38.2 0.3 43 34 1978 1976 1996 2001 normal 2 38.6 36.6 2.0 57 20 1978 2017 2001 1999 top-third 3 40.0 37.4 2.6 65 12 1977 2017 2001 1998 top-third 4 42.7 39.6 3.1 70 6 1977 2017 2001 1949 top-tenth 5 45.3 43.1 2.2 69 7 1977 2017 2001 1972 top-tenth 6 48.6 47.3 1.3 59 16 1977 2017 2001 1999 top-third 7 52.4 51.2 1.2 62 13 1977 2017 2001 1999 top-third 2006,2023 8 54.9 54.3 0.6 55 20 1977 2017 2001 1999 top-third 2005 9 56.7 56.3 0.4 54 21 1977 2017 2001 2000 top-third 2005,2021 10 57.5 57.1 0.4 53 22 1977 2017 2001 2000 top-third 2000 11 57.7 57.1 0.6 60 15 1977 2017 2001 2000 top-third 1999,2000,2005 12 56.2 56.2 0.0 49 26 1977 2017 2001 2000 normal 1988,2000 18 52.6 53.2 -0.6 35 39 1978 2017 2001 2000 normal 1952,1956,2011 24 55.6 56.1 -0.5 33 41 1978 2017 2001 2001 normal 1956,1976,1995,2001,2011 36 55.8 56.1 -0.3 43 30 1979 2018 1999 2001 normal 1990,2005,2010 48 56.0 56.1 -0.1 51 21 1964,1980 2020 2001 1995 top-third 1954,1957,1974,1990,1991,2011,2012 60 55.8 56.1 -0.3 38 33 1981 2020 2001 1996 normal 1958,2007,2010