1991-2020 Degrees Fahrenheit 1 48.6 47.2 1.4 43 18 2018 2010 1973 1968 top-third 2 41.4 41.3 0.1 38 23 1965 2012 1972 1973 normal 2008,2020 3 35.0 36.3 -1.3 25 36 1978 2012 1972 1973 normal 2008,2019 4 32.8 33.4 -0.6 35 26 1978 2012 1972 1973 normal 2008 5 31.6 32.7 -1.1 28 33 1978 2012 1972 1973 normal 1967,1980 6 32.8 33.8 -1.0 28 32 2014 2012 1972 1973 normal 1988 7 36.1 36.3 -0.2 34 26 1978 2012 1972 1973 normal 8 39.6 39.7 -0.1 38 22 1977,1978 2012 1973 1974 normal 2005 9 43.4 43.1 0.3 41 19 1978 2012 1973 1974 top-third 1985 10 46.3 46.0 0.3 41 19 1977 2012 1973 1974 top-third 11 48.6 48.1 0.5 44 16 1978 2012 1973 1974 top-third 1998 12 49.1 49.0 0.1 39 21 1982 2012 1973 1974 normal 18 44.2 43.9 0.3 44 15 1979 2017 1973 1974 top-third 24 48.7 48.9 -0.2 38 21 1978 2017 1973 1974 normal 1984,1988 36 48.6 48.9 -0.3 34 24 1979 2013 1973 1974 normal 1989,2004 48 48.4 48.9 -0.5 24 33 1980 2013 1973 1974 normal 1986,1989,1990,2004 60 47.9 48.9 -1.0 16 40 1982 2020 1973 1974 bottom-third 1985,1994