Hurrell Station-Based Monthly NAO Index Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1865 -0.6 -1.2 0.2 -0.2 -0.4 0.0 0.5 1.5 1.8 -2.0 -0.9 0.8 1866 0.5 0.8 -0.6 -2.3 -2.0 0.9 -0.5 -0.2 2.4 -0.3 -0.5 0.2 1867 -3.5 1.1 -4.3 1.8 -4.2 0.1 -2.0 1.9 1.4 2.2 -3.5 -0.1 1868 0.7 3.0 3.6 1.7 2.3 3.1 0.4 1.5 -2.8 3.5 -1.8 -0.1 1869 1.0 2.5 0.2 -0.2 -2.7 -1.9 -0.3 -1.0 -0.4 -1.4 1.4 0.0 1870 0.4 -2.8 -2.0 1.1 1.5 0.3 0.5 -3.6 0.2 0.9 -2.1 -3.0 1871 2.0 -0.3 0.9 -2.6 -1.5 -0.9 0.8 0.0 -2.2 0.2 -3.1 1.1 1872 1.0 -0.7 -1.1 -0.5 1.0 0.2 -2.3 -2.4 -1.8 1.6 0.4 -0.5 1873 1.3 -0.6 1.2 -3.3 -0.9 1.9 -0.1 3.1 -2.2 1.7 -1.9 0.6 1874 1.5 0.9 0.9 2.0 -1.3 0.1 0.6 0.9 1.4 1.8 -0.2 0.1 1875 -0.7 -1.0 -0.8 -1.8 2.4 3.2 -1.1 -1.6 -1.5 0.1 -3.1 -0.6 1876 0.8 -0.7 0.5 -0.6 0.8 3.3 1.7 0.3 -3.7 -1.9 -4.4 -2.1 1877 0.9 1.1 0.1 -3.1 -2.8 -0.1 1.3 -5.5 -3.2 0.0 2.2 2.5 1878 0.5 -0.2 0.2 -2.7 -0.8 -1.2 0.4 -3.5 1.0 -1.4 -3.1 -5.5 1879 -0.9 0.9 1.2 -0.2 1.6 -1.4 -0.4 -0.7 2.9 -0.3 -3.9 -1.2 1880 -0.8 1.0 0.5 1.3 -0.6 -0.2 -3.6 -0.4 -1.1 -4.7 1.0 -2.2 1881 -5.9 -0.9 -2.3 -1.9 0.9 1.2 1.7 -0.9 -2.2 -0.9 1.4 2.7 1882 1.0 0.6 3.6 -1.3 -1.3 0.1 1.8 0.7 1.6 0.3 1.6 -1.4 1883 0.7 2.4 -2.4 1.3 1.3 -2.3 -2.5 1.3 -0.7 2.5 1.9 0.7 1884 0.7 0.8 1.3 -2.0 0.3 0.9 -3.0 0.9 1.4 1.4 -1.1 2.1 1885 -0.4 -1.8 0.9 1.2 -1.6 1.7 0.3 -4.9 1.9 -0.3 -1.2 -1.3 1886 0.3 -0.1 -0.9 -1.2 -1.2 0.8 0.7 3.0 -1.2 0.7 1.6 -0.2 1887 1.7 1.1 -1.9 -3.2 0.5 -2.0 -0.3 -2.3 -0.7 -3.3 -1.1 -2.7 1888 -1.5 -1.6 -1.5 -0.8 -1.5 -1.7 -1.7 -0.4 -3.0 -3.1 2.2 1.4 1889 1.2 0.2 -0.2 1.7 0.5 1.7 -3.0 1.5 -1.2 1.0 1.7 3.1 1890 2.3 -0.7 2.0 1.8 -0.6 1.7 1.4 1.1 1.3 0.0 2.7 -0.8 1891 0.2 0.9 -1.2 -1.6 -0.8 -4.0 -2.8 0.2 1.6 1.1 0.0 1.7 1892 0.5 -1.8 -1.4 -0.6 -2.2 -1.6 0.0 -0.2 2.2 -3.2 0.7 -1.3 1893 -2.1 0.8 -0.4 -0.2 -1.2 -2.6 0.2 -2.8 1.7 0.4 -2.3 2.3 1894 0.5 3.1 1.7 1.8 -0.8 2.7 1.2 0.3 -4.0 -3.1 2.2 0.6 1895 -1.7 -4.9 1.0 -0.7 0.6 -0.4 0.1 -0.5 0.1 -2.8 -0.6 -0.5 1896 -0.9 0.9 2.6 2.5 1.2 -0.6 2.3 0.0 -0.1 -2.5 -0.9 1.8 1897 -1.5 1.1 1.0 3.6 0.1 -2.6 -1.0 1.4 1.0 -2.1 -0.5 0.6 1898 1.2 1.2 -0.5 2.2 -1.1 -1.5 -1.5 1.1 -0.8 -0.9 0.9 0.6 1899 -1.3 -1.6 -2.1 -0.3 -1.4 1.4 2.0 -2.6 1.4 -2.0 0.6 -0.9 1900 1.8 -3.1 -2.1 0.8 0.7 -0.7 -1.0 0.5 2.3 -0.3 2.2 1.2 1901 0.0 -2.9 -0.6 1.3 -1.7 1.6 1.2 1.0 1.2 2.0 -2.4 0.1 1902 -0.3 -2.8 0.7 -1.9 0.9 -4.0 -2.4 -1.6 -2.2 0.5 0.0 0.6 1903 0.1 1.8 3.6 -0.1 1.2 -3.6 -0.3 0.8 -0.6 -0.9 0.8 0.5 1904 1.8 0.9 0.6 4.1 0.8 -0.7 -1.6 -1.9 1.1 0.2 -0.5 -1.3 1905 0.4 1.4 1.7 -1.7 1.4 -0.7 0.5 0.5 1.3 -1.9 0.9 -0.3 1906 1.8 1.8 -0.4 2.5 -2.9 -1.6 2.9 -1.8 1.2 1.5 0.1 1.5 1907 0.8 1.6 3.2 1.6 -2.8 0.7 -2.4 -0.5 -0.1 0.1 1.8 0.6 1908 0.9 2.0 2.3 -1.2 1.1 1.1 -0.4 -0.4 0.3 -1.0 0.2 1.8 1909 1.4 -0.1 -1.9 0.4 -2.1 -0.9 3.3 2.5 -1.6 2.1 -1.9 -2.5 1910 2.0 3.4 1.7 -1.0 2.6 0.4 -0.6 -1.3 -1.3 -0.8 -1.9 -0.4 1911 0.8 0.8 0.2 -0.7 3.2 0.0 -1.8 -1.0 -0.1 -0.7 0.5 0.9 1912 -1.1 -2.4 1.9 1.1 0.6 0.0 -0.7 -1.4 -2.3 1.5 0.9 1.9 1913 0.5 0.3 3.1 2.7 1.3 1.7 -1.0 1.0 -1.6 -1.9 3.6 0.3 1914 -0.5 1.4 1.3 1.4 2.8 2.4 -0.5 0.7 -0.2 -0.4 0.1 1.4 1915 0.8 0.9 -3.2 3.1 -2.7 -2.6 0.3 -2.6 -2.0 1.4 -2.8 -2.7 1916 2.0 1.9 -3.0 1.0 -0.3 -1.9 0.4 -1.6 -1.1 2.4 -0.3 -3.7 1917 -2.3 -1.2 -0.4 -2.6 -2.8 0.5 -1.7 -0.4 1.8 1.8 1.7 -1.8 1918 -4.5 2.5 0.8 -0.4 0.4 1.5 -3.0 1.2 0.8 2.0 0.3 0.7 1919 0.0 -2.7 -0.4 1.0 -0.7 3.3 -1.2 1.0 0.8 -1.2 -1.6 2.3 1920 2.3 1.0 3.6 -1.8 2.3 -0.3 3.1 -1.0 1.3 -0.2 2.1 -1.8 1921 1.6 0.3 3.1 -0.5 2.8 -1.0 -1.2 0.8 -0.2 -1.2 -0.6 2.7 1922 0.6 2.6 0.5 -0.1 1.4 2.9 2.0 1.6 1.7 -3.7 -0.3 0.8 1923 1.5 0.8 0.0 0.5 -0.8 0.8 2.4 0.2 1.8 1.3 0.2 1.2 1924 0.4 -0.8 -3.5 -2.2 -0.3 -0.1 1.5 1.8 1.2 0.7 0.6 2.8 1925 1.0 2.0 -1.1 2.1 1.8 1.1 2.7 1.1 -0.1 -1.6 -1.6 -4.3 1926 0.3 0.4 0.2 0.9 -1.4 -1.8 0.7 0.8 -1.1 -2.8 2.1 -0.9 1927 1.9 0.3 1.9 0.9 -2.3 -0.2 -0.3 0.2 0.0 -3.2 0.5 -3.5 1928 3.0 1.7 -1.0 0.8 -3.1 -2.9 0.8 -1.5 -1.0 2.0 1.7 0.6 1929 -4.1 -0.3 -1.4 -3.0 2.3 -0.7 -0.1 0.3 1.3 1.9 1.9 2.6 1930 1.4 -0.2 -1.1 -0.3 2.5 2.8 -0.5 0.0 -2.8 0.6 1.0 2.1 1931 -0.1 1.8 -3.4 1.1 -0.7 -1.9 2.1 -1.9 -1.4 -0.9 2.4 0.0 1932 1.1 -3.5 -1.3 0.7 -1.5 -1.3 1.8 1.6 0.3 1.8 0.5 0.1 1933 1.5 -2.1 0.7 -1.9 0.3 2.2 2.3 1.8 -0.4 -2.1 0.3 -0.6 1934 1.7 0.6 2.2 -2.0 2.8 -2.0 0.4 2.4 2.1 0.9 -0.5 -1.1 1935 -0.1 2.2 0.2 -2.0 -1.8 0.8 3.8 2.0 0.4 3.6 1.7 -1.7 1936 -3.0 -2.6 -0.9 -0.9 0.9 0.5 1.1 2.1 -2.3 2.4 1.9 1.3 1937 0.6 0.1 -2.0 1.0 1.7 -0.6 -0.1 1.3 1.4 -0.6 -3.1 -1.1 1938 2.2 -0.8 2.4 -1.9 1.1 1.3 2.2 1.3 1.6 3.8 2.1 0.7 1939 -2.1 2.2 0.7 -0.4 0.3 -0.4 -0.6 1.3 -4.0 -0.6 1.5 -1.7 1940 -2.6 -2.1 -1.5 -0.5 -0.2 1.8 0.6 0.7 0.1 -0.2 1.5 -0.1 1941 -2.9 -0.9 -0.9 -1.7 0.3 0.3 1.7 0.2 -1.2 -1.1 -0.2 0.8 1942 1.6 -2.7 -2.0 -0.4 -0.1 -2.0 1.5 1.8 2.1 1.0 -1.5 0.3 1943 -0.7 2.7 0.7 3.4 0.6 0.7 0.4 -1.6 2.6 0.8 1.6 1.1 1944 1.0 -0.2 -1.8 -0.4 0.7 -0.4 -3.0 1.7 1.1 2.0 0.5 1.2 1945 -2.2 2.5 0.8 -2.2 -0.3 0.5 0.2 1.4 0.5 -1.9 -2.9 -2.1 1946 1.4 -0.2 0.2 3.0 -2.5 2.7 2.3 2.0 1.3 -2.7 -0.9 1.6 1947 -0.2 -4.2 -2.8 3.3 -0.2 -0.1 0.5 -0.2 2.4 -0.2 -1.9 -2.1 1948 0.6 -0.5 2.0 1.6 -0.4 -0.4 -0.6 -0.2 0.1 1.5 -1.6 -0.5 1949 0.9 1.9 -0.2 2.5 -0.1 -1.7 -0.8 -1.1 -0.8 0.1 1.6 0.4 1950 0.0 1.5 0.0 1.6 -2.2 -0.1 -0.1 1.4 3.0 1.2 -0.6 -1.0 1951 1.0 1.4 -2.1 -1.6 -1.8 -2.8 -0.3 2.2 0.2 1.5 -0.1 2.4 1952 2.0 -1.2 -2.1 2.2 -2.0 -0.2 0.9 -0.5 -1.8 -0.2 -1.8 -0.8 1953 -1.2 0.6 0.5 -2.7 -1.2 1.5 2.2 2.1 1.4 1.6 2.1 0.9 1954 0.3 1.6 0.7 0.9 -1.6 1.1 3.3 0.0 2.4 1.0 2.1 1.6 1955 -2.0 -2.2 -2.6 0.8 0.0 -0.2 1.4 1.3 3.7 -1.3 -3.1 -0.8 1956 -0.8 -2.2 0.6 -1.6 4.9 1.0 -0.8 -1.2 -0.7 0.9 1.7 1.7 1957 1.8 -1.0 -1.7 1.0 0.3 -3.1 -1.6 0.8 -1.9 2.5 -1.9 1.3 1958 -0.6 -2.4 -2.5 1.5 -0.6 -2.0 -2.1 -0.5 -1.3 1.6 1.7 -1.0 1959 -3.0 1.6 1.7 0.8 -0.4 1.4 1.9 -0.2 -0.2 1.5 1.2 2.0 1960 -2.0 -3.3 -0.8 1.5 0.0 0.6 2.0 -3.5 1.4 -2.9 0.5 2.1 1961 0.9 1.0 0.3 -1.3 -1.2 3.5 0.3 1.3 2.1 1.8 -0.2 -4.5 1962 2.1 0.9 -4.2 0.4 -0.3 -0.4 -2.4 0.9 -0.6 0.0 -0.4 -1.2 1963 -5.1 -1.2 0.9 -0.9 5.2 -1.8 -2.3 0.3 2.0 2.1 -1.2 -2.5 1964 -1.5 -1.5 -1.3 1.2 1.6 -0.3 1.6 -3.0 -0.9 1.2 0.5 0.0 1965 -0.2 -3.7 -1.2 3.0 -0.7 1.1 -0.9 0.6 -0.2 -0.6 -1.9 0.7 1966 -3.5 -2.5 0.4 -1.1 2.3 0.9 0.8 -2.9 -1.2 -3.4 0.7 1.8 1967 -1.6 1.4 2.4 0.7 -0.4 2.1 -0.5 0.2 0.1 2.0 1.0 -0.9 1968 0.5 -1.7 1.7 -1.9 -0.8 0.3 -3.6 -1.1 -1.0 -3.1 -1.7 -1.4 1969 -3.3 -3.2 -2.6 1.5 -1.3 0.0 1.2 -0.6 1.8 0.5 -0.6 1.3 1970 -2.9 1.1 -1.3 0.9 2.0 0.6 -0.5 -0.6 0.3 -0.6 0.0 -1.5 1971 -1.2 1.0 0.2 -1.8 2.4 -1.9 -1.9 2.2 -1.8 -0.4 1.1 0.8 1972 0.4 0.6 1.1 1.2 2.7 3.1 -0.8 0.1 -3.1 -1.4 1.3 1.7 1973 0.5 2.3 0.9 -3.3 -0.8 1.9 0.5 0.8 -0.3 -1.1 -1.2 0.0 1974 2.2 1.1 0.3 -0.4 -0.3 -1.0 1.1 0.0 1.0 -0.1 0.8 1.8 1975 1.3 -0.6 -0.3 0.1 -1.0 -0.9 -0.7 -0.4 2.0 -1.0 1.2 -0.6 1976 0.7 1.2 2.3 0.4 2.6 0.7 -3.0 -2.6 -4.6 1.6 1.2 -2.6 1977 -1.7 -1.0 -0.5 0.6 -0.4 -1.5 0.5 -0.5 -0.9 0.7 -0.7 -1.6 1978 1.6 -3.1 2.9 -1.9 1.5 1.2 -2.3 -2.1 0.2 -0.2 2.7 -3.1 1979 -2.6 -1.0 1.2 -1.5 -0.1 0.6 0.5 0.0 0.4 0.2 1.3 1.3 1980 -1.7 0.5 0.0 -0.2 -2.1 1.3 -1.6 -2.1 1.6 -1.3 -2.7 1.5 1981 1.0 1.2 -1.1 -1.2 0.1 -1.8 1.6 0.4 -0.3 0.3 -0.8 -1.6 1982 -1.3 1.7 2.5 -0.6 1.0 -3.0 -0.8 2.5 0.5 1.1 2.2 2.6 1983 2.6 -1.1 2.0 -1.2 -0.4 0.6 -0.5 1.4 -1.9 2.0 -3.6 0.3 1984 3.4 1.6 -1.9 -1.0 1.6 0.3 -1.7 0.5 0.4 1.3 0.3 1.5 1985 -2.7 -1.5 0.6 0.2 -0.9 -1.9 0.3 1.2 -1.7 -0.4 -2.4 -1.2 1986 2.4 -2.7 3.9 0.0 2.4 0.6 0.6 -3.7 -3.3 3.6 3.3 1.9 1987 -3.5 -0.7 -0.1 0.6 -1.8 -1.1 0.0 -3.3 -0.4 0.8 0.1 -2.3 1988 1.1 0.3 0.9 -2.4 -0.4 0.2 0.8 1.5 0.6 -1.6 -2.2 0.5 1989 2.4 3.2 3.2 0.8 0.3 -1.2 -0.6 2.4 -0.4 0.9 -1.4 -3.4 1990 3.0 3.2 2.3 3.1 -2.0 1.0 -0.1 0.9 -0.7 0.5 -1.1 1.1 1991 0.7 0.5 -0.1 1.1 1.0 -0.9 -1.4 1.6 -0.5 -0.3 1.6 0.2 1992 -1.0 2.0 2.0 1.8 0.3 -0.2 -0.2 2.3 -0.5 -1.2 2.2 1.2 1993 2.1 0.3 1.2 1.5 -3.6 -0.3 -0.2 -0.2 -2.6 -0.7 2.5 2.6 1994 2.0 -0.4 4.4 1.1 -0.5 2.1 0.7 -1.0 -0.1 -1.2 0.2 1.6 1995 1.4 2.3 1.8 -1.9 -0.8 -2.1 -1.4 -0.8 0.6 -0.3 -3.0 -3.8 1996 -1.8 0.9 -2.6 -1.0 -1.8 0.7 1.2 0.6 -0.6 1.6 1.0 -3.6 1997 -2.4 3.7 1.2 -1.8 -1.9 -3.1 1.1 0.7 -0.8 -2.6 0.1 -0.5 1998 -0.7 0.7 0.5 0.7 -0.2 -1.0 0.3 1.5 -2.0 1.0 0.9 1.6 1999 1.3 2.2 0.2 0.0 0.4 1.2 -1.8 -2.6 0.9 0.4 0.8 1.7 2000 0.1 3.1 0.4 -2.5 1.4 -0.5 -2.9 0.4 0.2 4.5 0.0 -2.2 2001 -0.1 -0.5 -1.5 1.4 -1.0 -1.9 0.3 0.6 -2.8 0.9 1.4 -4.1 2002 0.5 1.7 0.9 2.2 1.9 1.9 1.6 0.6 -4.4 -2.0 1.3 -2.4 2003 0.4 1.2 0.5 -1.9 0.8 -0.5 0.4 -2.0 -0.6 -1.0 1.4 -1.1 2004 0.2 -1.4 1.5 1.7 0.9 -1.5 -0.8 -1.5 2.0 -2.0 -0.2 2.6 2005 1.0 -0.6 -3.0 0.2 -1.6 -1.4 -0.5 1.8 1.2 -1.5 0.7 -0.7 2006 1.0 -0.7 -1.8 1.0 -0.6 0.0 -0.3 -0.9 -0.4 -2.4 1.2 2.1 2007 1.1 -0.2 3.1 -0.1 2.9 -3.5 -1.0 -0.2 -0.1 0.9 -1.2 0.9 2008 1.4 0.4 1.6 -2.8 -2.1 -0.2 0.0 2.0 0.2 3.1 1.3 0.5 2009 1.6 -0.2 1.7 2.8 2.7 -3.8 -2.0 2.2 1.4 -2.2 2.1 -4.6 2010 -1.9 -3.6 -1.5 -2.5 -0.8 -0.3 1.7 -1.9 -0.2 -0.8 -1.5 -5.6 2011 -1.3 1.9 0.4 2.1 1.8 -0.8 0.3 -1.4 1.1 1.6 1.2 3.5 2012 1.7 1.3 0.9 0.4 -3.3 -2.5 -0.6 -2.1 -0.1 -3.3 1.6 -0.4 2013 0.8 0.1 -4.3 -0.4 3.0 1.8 -1.5 2.7 -0.2 -1.0 1.6 2.8 2014 2.0 2.2 2.2 -0.4 1.4 -1.7 0.2 -0.8 -2.1 0.1 0.6 2.9 2015 3.5 2.4 3.1 -0.1 1.9 -0.7 -2.3 1.0 -1.6 -0.6 2.7 0.8 2016 0.0 2.4 1.4 -1.7 -0.8 -0.2 0.4 0.2 2.8 -1.2 1.0 0.9 2017 -0.4 1.2 1.5 -1.0 -2.4 1.4 1.8 0.3 2.3 0.7 -1.2 0.8 2018 2.4 0.9 -1.0 1.2 3.9 0.0 1.5 2.2 0.6 1.0 -0.2 0.1 2019 0.1 0.1 2.6 0.0 -1.8 -2.5 -0.9 -0.5 1.0 -1.3 0.4 0.8 2020 2.1 3.3 1.8 -1.5 -1.0 -1.0 0.4 -0.4 1.1 0.7 1.7 0.6 2021 -1.5 -0.2 1.1 -3.6 0.1 1.3 -1.2 -1.7 0.7 0.5 0.4 -0.9 2022 0.6 3.1 0.8 -1.9 1.1 1.6 0.5 -0.1 -1.1 -999. -999. -999.