1991-2020 Degrees Fahrenheit 1 64.0 67.2 -3.2 12 70 1969 2005 1985 1988 bottom-third 2 60.2 62.5 -2.3 23 59 1947 2018 1983 1988 bottom-third 1996 3 54.3 56.6 -2.3 16 66 1947 1987 1983 1988 bottom-third 1997 4 47.0 50.4 -3.4 10 72 1947 2012 1979 1988 bottom-third 5 39.8 44.4 -4.6 6 76 1947 2012 1979 1988 bottom-tenth 6 36.7 39.8 -3.1 19 62 1950,1979 2012 1982 1988 bottom-third 2008 7 34.2 37.3 -3.1 20 61 1979 2012 1982 1988 bottom-third 2008 8 34.4 37.0 -2.6 26 53 1979 2012 1982 1988 bottom-third 1977,2019 9 35.2 38.2 -3.0 13 66 1979 2012 1982 1988 bottom-third 1959,1963,1970 10 37.8 40.5 -2.7 19 60 1943 2012 1982 1988 bottom-third 1971,1993 11 40.9 43.1 -2.2 22 57 1943,1951 2012 1982 1988 bottom-third 1960,1969 12 43.7 45.4 -1.7 31 48 1951 2012 1986 1988 normal 2015 18 42.2 43.6 -1.4 45 33 1951 1999 1986 1988 normal 1953,1955,1964,1986,2019 24 44.5 45.4 -0.9 46 30 1952 2017 1986 1988 normal 1981,1995 36 45.3 45.4 -0.1 56 18 1953,1979 2000 1988 1989 top-third 48 44.9 45.4 -0.5 45 27 1968,1980 2001,2002 1986 1988 normal 1998,2011 60 44.9 45.4 -0.5 42 28 1947,1969 2002 1986 1988 normal