1991-2020 Degrees Fahrenheit 1 45.8 41.6 4.2 68 9 1960 2012 1999 1990 top-third 2 41.5 37.1 4.4 69 8 1978 2012 1999 1998 top-tenth 3 36.7 34.6 2.1 61 16 1978 2012 1999 1998 top-third 4 36.1 34.6 1.5 58 18 1978 2012 1999 1998 top-third 5 38.3 36.4 1.9 63 13 1978 2012 1999 1998 top-third 6 41.0 39.6 1.4 61 15 1977 2012 1999 1998 top-third 7 44.7 43.5 1.2 60 16 1977 2017 1999 1999 top-third 1972,1999 8 48.1 47.3 0.8 57 19 1977 2017 1997 1999 top-third 1950 9 51.5 50.4 1.1 62 14 1977 2017 1999 1991 top-third 1983,1987,2021 10 53.7 52.5 1.2 64 12 1977 2017 1999 1976 top-third 1954,1974,2021 11 54.7 53.5 1.2 63 13 1977 2017 1999 1992 top-third 2008 12 54.7 53.5 1.2 67 9 1977 2012 1999 1992 top-third 18 49.9 48.8 1.1 65 10 1978 2017 1998 1999 top-third 24 54.6 53.4 1.2 67 8 1978 2017 1999 2000 top-third 36 54.0 53.4 0.6 64 10 1979 2018 1999 1955 top-third 1955,2014 48 53.6 53.4 0.2 57 16 1980 2019,2020 1999 1992 top-third 1992,2017 60 53.2 53.3 -0.1 42 30 1981 2020 1999 1992 normal 1955,1987,1988,2001,2004,2011