1991-2020 Degrees Fahrenheit 1 60.2 63.5 -3.3 7 53 1993 2005 1989 1991 bottom-third 2 62.9 67.3 -4.4 1 59 1992 2005 1992 1991 lowest 3 64.5 69.1 -4.6 1 59 1992 2005,2016 1992 1991 lowest 4 64.6 69.1 -4.5 1 59 1992 2005 1992 1991 lowest 5 63.2 67.1 -3.9 1 59 1992 2018 1992 1991 lowest 6 60.1 63.8 -3.7 1 59 1992 2010 1992 1991 lowest 7 56.4 59.8 -3.4 1 59 1992 2012 1992 1991 lowest 8 53.2 55.7 -2.5 8 52 1978 2012 1989 1991 bottom-third 9 50.4 52.2 -1.8 18 42 1978 2012 1989 1991 bottom-third 1970,1974 10 48.4 50.1 -1.7 21 39 1978 2012 1989 1991 normal 1977,1986,1993 11 47.3 49.1 -1.8 17 42 1978 2012 1984 1991 bottom-third 1974,1984,2009 12 47.7 49.3 -1.6 22 37 1978 2012 1989 1991 normal 18 53.6 54.2 -0.6 32 27 1979 2012 1990 1991 normal 1985 24 49.2 49.3 -0.1 38 20 1979 2017 1990 1991 normal 2010 36 48.9 49.3 -0.4 34 23 1979 2012 1991 1988 normal 1985 48 48.5 49.3 -0.8 22 34 1980 2013 1989 1991 normal 1989 60 48.5 49.2 -0.7 23 32 1982 2002 1990 1991 normal 1990,1995