1991-2020 Degrees Fahrenheit 1 49.6 53.7 -4.1 9 69 1949 2015 1989 1988 bottom-third 2 50.0 52.6 -2.6 22 56 1949 2015 1989 1988 bottom-third 1976 3 50.2 52.2 -2.0 25 53 1949 2015 1989 1988 bottom-third 1956 4 51.9 53.3 -1.4 32 46 1949 2015 1989 1988 normal 1953,2012 5 53.7 55.2 -1.5 32 46 1949 2015 1989 1988 normal 1983,2023 6 55.1 57.0 -1.9 24 54 1949 2015 1979 1989 bottom-third 1953 7 56.4 58.1 -1.7 26 52 1949 2015 1982 1989 bottom-third 1982 8 57.3 58.9 -1.6 28 49 1949 2015 1982 1989 normal 2001 9 57.9 59.3 -1.4 27 49 1949 2015 1983 1989 normal 1995 10 58.2 59.4 -1.2 31 45 1949 2015 1983 1989 normal 1982,2013 11 58.5 59.2 -0.7 46 30 1949 2015 1989 1989 normal 1958,1985,1989,1992 12 58.2 58.9 -0.7 44 32 1949 2015 1987 1989 normal 1960,1987 18 57.2 58.2 -1.0 32 43 1949,1950 2016 1983 1989 normal 1980,1982,1995,1999,2013 24 58.3 58.8 -0.5 43 31 1950 2016 1987 1989 normal 1987,2002 36 58.6 58.8 -0.2 53 19 1950,1957 2017 1989 1989 top-third 1988,1989,2011 48 58.5 58.8 -0.3 50 20 1952,1957 2018 1989 1989 top-third 1989,2000,2004 60 58.5 58.7 -0.2 47 21 1953,1956,1957 2018 1989 1989 top-third 1989