MEI Index (last update: 8 September 2016)

Bimonthly MEI values (in 1/1000 of standard deviations), starting with Dec1949/Jan1950, thru last
month.  More information on the MEI can be found on the MEI homepage.
Missing values are left blank.  Note that values can still change with each monthly update, even 
though such changes are typically smaller than +/-0.1.  All values are normalized for each bimonthly
season so that the 44 values from 1950 to 1993 have an average of zero and a standard deviation of "1".  
Responses to 'FAQs' can be found below this table:

YEAR    DECJAN  JANFEB  FEBMAR  MARAPR  APRMAY  MAYJUN  JUNJUL  JULAUG  AUGSEP  SEPOCT  OCTNOV  NOVDEC
1950	-1.043	-1.162	-1.312	-1.104	-1.433	-1.391	-1.296	-1.053	-.627	-.424	-1.171	-1.263
1951	-1.078	-1.189	-1.222	-.523	-.36	.349	.666	.829	.734	.731	.709	.477
1952	.421	.136	.063	.22	-.309	-.723	-.316	-.378	.313	.274	-.359	-.132
1953	.032	.385	.256	.682	.784	.218	.368	.213	.484	.078	.063	.316
1954	-.044	-.032	.162	-.567	-1.416	-1.564	-1.378	-1.471	-1.165	-1.361	-1.139	-1.114
1955	-.766	-.698	-1.152	-1.634	-1.642	-2.243	-1.998	-2.073	-1.831	-1.767	-1.852	-1.879
1956	-1.447	-1.323	-1.413	-1.132	-1.317	-1.502	-1.259	-1.131	-1.371	-1.469	-1.058	-1.04
1957	-.944	-.364	.134	.353	.866	.769	.908	1.148	1.148	1.077	1.122	1.24
1958	1.474	1.442	1.32	1.013	.719	.864	.693	.427	.173	.202	.468	.67
1959	.549	.788	.496	.197	.013	-.018	-.134	.114	.102	-.067	-.176	-.255
1960	-.297	-.257	-.094	-.019	-.335	-.254	-.34	-.251	-.466	-.363	-.341	-.438
1961	-.167	-.261	-.097	0	-.288	-.137	-.216	-.304	-.293	-.526	-.44	-.634
1962	-1.082	-.988	-.724	-1.039	-.91	-.852	-.701	-.543	-.554	-.676	-.625	-.506
1963	-.73	-.861	-.69	-.792	-.477	-.087	.401	.597	.749	.817	.843	.739
1964	.867	.465	-.269	-.563	-1.242	-1.115	-1.405	-1.503	-1.311	-1.225	-1.242	-.945
1965	-.554	-.349	-.276	.053	.49	.915	1.36	1.443	1.399	1.217	1.355	1.253
1966	1.305	1.178	.678	.528	-.152	-.168	-.136	.155	-.091	-.035	.007	-.198
1967	-.474	-.924	-1.068	-1.059	-.455	-.266	-.521	-.395	-.616	-.686	-.425	-.378
1968	-.622	-.74	-.629	-.965	-1.095	-.771	-.527	-.102	.224	.426	.59	.35
1969	.664	.844	.452	.623	.696	.82	.467	.218	.165	.508	.67	.392
1970	.367	.411	.215	-.023	-.126	-.659	-1.089	-1.016	-1.258	-1.091	-1.078	-1.224
1971	-1.221	-1.521	-1.807	-1.888	-1.464	-1.448	-1.23	-1.225	-1.465	-1.424	-1.33	-.998
1972	-.595	-.422	-.262	-.196	.464	1.069	1.827	1.821	1.547	1.651	1.747	1.761
1973	1.72	1.497	.845	.481	-.106	-.769	-1.081	-1.347	-1.729	-1.671	-1.496	-1.844
1974	-1.934	-1.793	-1.76	-1.673	-1.077	-.67	-.769	-.671	-.624	-1.053	-1.243	-.906
1975	-.544	-.597	-.884	-.963	-.863	-1.15	-1.519	-1.73	-1.877	-1.986	-1.771	-1.752
1976	-1.613	-1.394	-1.246	-1.184	-.496	.307	.615	.664	1.029	.938	.49	.547
1977	.516	.271	.131	.539	.326	.451	.866	.695	.801	.993	.97	.86
1978	.77	.893	.936	.191	-.388	-.579	-.433	-.2	-.386	-.024	.178	.392
1979	.598	.361	-.015	.283	.38	.423	.369	.625	.779	.666	.744	.996
1980	.678	.589	.69	.907	.961	.907	.749	.336	.279	.209	.252	.098
1981	-.254	-.163	.457	.669	.161	-.019	-.048	-.088	.178	.108	-.036	-.137
1982	-.268	-.138	.106	-.009	.429	.944	1.604	1.799	1.808	2.019	2.433	2.418
1983	2.691	2.909	3.011	2.824	2.542	2.24	1.763	1.178	.481	.034	-.131	-.176
1984	-.327	-.533	.143	.347	.131	-.079	-.084	-.154	-.101	.009	-.344	-.596
1985	-.559	-.594	-.718	-.481	-.707	-.133	-.143	-.367	-.513	-.135	-.057	-.299
1986	-.307	-.196	.04	-.11	.35	.306	.383	.775	1.122	.98	.865	1.183
1987	1.243	1.192	1.719	1.866	2.14	1.964	1.859	1.999	1.888	1.643	1.271	1.284
1988	1.116	.697	.487	.353	.119	-.622	-1.145	-1.303	-1.499	-1.315	-1.44	-1.306
1989	-1.128	-1.271	-1.037	-.795	-.435	-.253	-.459	-.497	-.277	-.314	-.045	.127
1990	.232	.555	.945	.442	.637	.484	.12	.131	.384	.28	.39	.357
1991	.32	.313	.405	.463	.759	1.1	1.023	1.024	.759	1.024	1.2	1.325
1992	1.749	1.864	1.993	2.275	2.129	1.748	1.018	.57	.52	.664	.589	.64
1993	.686	.979	.99	1.409	1.998	1.591	1.17	1.042	.987	1.063	.839	.595
1994	.349	.197	.174	.465	.573	.788	.88	.773	.903	1.419	1.29	1.229
1995	1.216	.961	.879	.466	.563	.508	.207	-.143	-.413	-.471	-.453	-.546
1996	-.63	-.581	-.227	-.42	-.127	.068	-.204	-.374	-.443	-.349	-.13	-.325
1997	-.489	-.595	-.222	.535	1.165	2.292	2.805	3.04	3.049	2.417	2.575	2.368
1998	2.503	2.792	2.768	2.685	2.212	1.292	.347	-.331	-.587	-.795	-1.099	-.941
1999	-1.094	-1.176	-1.019	-.982	-.66	-.361	-.507	-.745	-.974	-.977	-1.042	-1.192
2000	-1.164	-1.207	-1.112	-.479	.169	-.053	-.184	-.145	-.219	-.372	-.712	-.551
2001	-.502	-.669	-.571	-.091	.233	.006	.27	.338	-.108	-.266	-.159	.028
2002	-.032	-.176	-.137	.401	.851	.913	.685	1.017	.859	.976	1.076	1.141
2003	1.199	.937	.831	.365	.111	.097	.144	.316	.459	.519	.536	.349
2004	.322	.356	-.056	.285	.539	.267	.541	.627	.531	.497	.815	.665
2005	.31	.81	1.055	.642	.836	.585	.49	.352	.288	-.149	-.376	-.576
2006	-.435	-.411	-.533	-.621	.008	.53	.691	.759	.825	.934	1.322	.998
2007	1.012	.542	.112	.015	.247	-.215	-.288	-.441	-1.092	-1.103	-1.119	-1.129
2008	-.968	-1.355	-1.583	-.874	-.368	.133	.054	-.266	-.561	-.72	-.502	-.608
2009	-.711	-.677	-.678	-.109	.361	.819	1.035	1.067	.805	1.038	1.088	1.041
2010	1.152	1.521	1.427	.95	.643	-.325	-1.156	-1.683	-1.954	-1.896	-1.523	-1.529
2011	-1.645	-1.53	-1.511	-1.392	-.288	-.075	-.228	-.519	-.713	-.939	-.886	-.912
2012	-.995	-.665	-.377	.127	.747	.835	1.098	.619	.328	.139	.21	.081
2013	.069	-.119	-.128	.069	.146	-.168	-.355	-.48	-.095	.135	-.027	-.255
2014	-.287	-.241	.032	.248	.976	.98	.882	.954	.602	.411	.772	.611
2015	.419	.468	.67	.97	1.584	2.045	1.948	2.366	2.527	2.225	2.308	2.123
2016	2.202	2.121	1.96	2.07	1.699	1.001	.312	.175


(1) If you are trying to relate the MEI to monthly values of, say, precipitation, it may be 
    expedient to use the MEI value of month(i-1) and month(i) as if it were the value for 
    month(i) only. Since it takes a week or so for the global atmosphere to respond to tropical
    SST anomalies, the resulting lag is thus built into the analysis (I have verified this for
    southwest U.S. precipitation).

(2) Next update: 8 October 2016 

(3) Are there MEI values available prior to 1950? YES, the link to the sister website for
    the MEI.ext is here.
    Numerical values for the MEI.ext are available 
    here.

(4) Why do I believe that the MEI is better for monitoring ENSO than the SOI or various SST
    indices?  In brief, the MEI integrates more information than other indices, it reflects
    the nature of the coupled ocean-atmosphere system better than either component, and it is
    less vulnerable to occasional data glitches in the monthly update cycles. Now, if you are
    interested in ENSO impacts in a very specific part of the world, I would suggest that you
    obtain other ENSO indices as well and establish which one best fits your needs. 
    For instance, in Australia, Darwin sea level pressure and/or the SOI may be more appropriate
    than the MEI. My claim here is that the MEI does a better job than other indices for the 
    overall monitoring of the ENSO phenomenon, including, for instance, world-wide correlations 
    with surface temperatures and rainfall.

(5) I have been asked about MEI-like indices for the Indian Ocean, and at present I have no such
    project under way, nor do I know of any such data.

(6) Given the integrative approach of the MEI, I am very hesitant to give out subsets of the data
    that make up the MEI (for instance, its SST or SLP components alone).  Therefore, I will not
    honor requests of that nature.

(7) If you are interested in MEI predictions, please contact me directly under my e-mail address:
    Klaus Wolter (klaus.wolter@noaa.gov).

Link to ranked MEI values is here.

Go back to MEI homepage.