MEI Index (updated: 7 September 2018)

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	-1.03	-1.133	-1.283	-1.071	-1.434	-1.412	-1.269	-1.042	-.597	-.406	-1.138	-1.235
1951	-1.049	-1.152	-1.178	-.511	-.374	.288	.679	.818	.773	.768	.726	.504
1952	.433	.138	.071	.224	-.307	-.756	-.305	-.374	.347	.306	-.328	-.098
1953	.044	.401	.277	.687	.756	.191	.382	.209	.527	.124	.099	.351
1954	-.036	-.027	.154	-.616	-1.465	-1.558	-1.355	-1.456	-1.138	-1.32	-1.113	-1.088
1955	-.74	-.669	-1.117	-1.621	-1.653	-2.247	-1.976	-2.05	-1.803	-1.725	-1.813	-1.846
1956	-1.408	-1.275	-1.371	-1.216	-1.304	-1.523	-1.244	-1.118	-1.327	-1.461	-1.014	-.993
1957	-.915	-.348	.108	.383	.813	.73	.926	1.132	1.158	1.114	1.167	1.268
1958	1.473	1.454	1.313	.991	.673	.812	.7	.421	.209	.237	.501	.691
1959	.553	.81	.502	.202	-.025	-.062	-.112	.111	.126	-.038	-.151	-.247
1960	-.287	-.253	-.082	.007	-.322	-.287	-.318	-.25	-.439	-.332	-.308	-.39
1961	-.15	-.235	-.073	.017	-.302	-.185	-.208	-.3	-.271	-.51	-.416	-.608
1962	-1.065	-.963	-.692	-1.04	-.89	-.87	-.683	-.538	-.528	-.642	-.598	-.482
1963	-.718	-.837	-.675	-.761	-.473	-.144	.404	.59	.778	.848	.866	.765
1964	.878	.481	-.256	-.545	-1.234	-1.15	-1.384	-1.486	-1.284	-1.196	-1.211	-.907
1965	-.536	-.329	-.259	.086	.464	.867	1.367	1.425	1.43	1.25	1.378	1.27
1966	1.307	1.186	.689	.515	-.178	-.193	-.116	.152	-.06	-.018	.022	-.181
1967	-.462	-.898	-1.05	-1.03	-.448	-.236	-.492	-.391	-.601	-.655	-.407	-.357
1968	-.602	-.727	-.635	-.944	-1.093	-.812	-.503	-.104	.244	.46	.607	.367
1969	.67	.849	.458	.622	.674	.801	.49	.212	.2	.537	.683	.417
1970	.38	.432	.228	.014	-.099	-.636	-1.055	-1.007	-1.226	-1.068	-1.063	-1.203
1971	-1.204	-1.507	-1.79	-1.839	-1.429	-1.42	-1.207	-1.213	-1.439	-1.399	-1.301	-.969
1972	-.575	-.398	-.256	-.166	.423	.966	1.826	1.8	1.574	1.667	1.74	1.787
1973	1.723	1.515	.87	.491	-.099	-.758	-1.056	-1.334	-1.712	-1.65	-1.482	-1.826
1974	-1.912	-1.768	-1.743	-1.62	-1.048	-.694	-.75	-.664	-.599	-1.031	-1.23	-.886
1975	-.522	-.576	-.85	-.927	-.838	-1.148	-1.497	-1.712	-1.853	-1.968	-1.748	-1.732
1976	-1.587	-1.366	-1.213	-1.157	-.483	.276	.633	.654	1.064	.978	.511	.565
1977	.529	.29	.145	.552	.31	.414	.888	.684	.824	1.016	.99	.877
1978	.777	.912	.935	.199	-.378	-.605	-.42	-.199	-.364	.003	.203	.406
1979	.608	.379	.002	.301	.374	.429	.396	.615	.801	.694	.759	1.004
1980	.677	.601	.684	.912	.958	.911	.769	.329	.302	.223	.27	.111
1981	-.25	-.14	.455	.669	.189	-.024	-.026	-.09	.209	.132	-.021	-.126
1982	-.258	-.125	.1	.008	.443	.93	1.612	1.778	1.835	2.061	2.441	2.425
1983	2.677	2.931	3.008	2.812	2.498	2.235	1.793	1.159	.507	.056	-.115	-.17
1984	-.314	-.509	.151	.39	.18	-.049	-.054	-.155	-.085	.026	-.332	-.585
1985	-.546	-.576	-.696	-.468	-.706	-.166	-.126	-.365	-.508	-.119	-.042	-.279
1986	-.293	-.183	.028	-.107	.353	.279	.401	.765	1.116	1.002	.89	1.202
1987	1.249	1.218	1.716	1.855	2.107	1.958	1.878	1.973	1.905	1.671	1.286	1.293
1988	1.115	.716	.495	.389	.193	-.582	-1.109	-1.295	-1.501	-1.313	-1.447	-1.311
1989	-1.103	-1.241	-1.035	-.76	-.393	-.242	-.43	-.494	-.287	-.319	-.058	.131
1990	.243	.573	.951	.46	.652	.511	.147	.127	.398	.303	.4	.362
1991	.319	.323	.399	.449	.741	1.051	1.044	1.008	.778	1.031	1.202	1.34
1992	1.747	1.886	1.985	2.247	2.085	1.735	1.045	.559	.518	.663	.595	.664
1993	.692	.99	.987	1.408	1.993	1.616	1.204	1.026	1.011	1.09	.848	.595
1994	.352	.193	.159	.465	.58	.803	.904	.762	.931	1.437	1.312	1.251
1995	1.219	.959	.845	.453	.57	.507	.234	-.147	-.416	-.461	-.463	-.537
1996	-.597	-.566	-.236	-.391	-.041	.087	-.173	-.374	-.426	-.338	-.134	-.325
1997	-.48	-.605	-.248	.527	1.132	2.275	2.825	3.002	3.057	2.423	2.551	2.344
1998	2.455	2.777	2.751	2.658	2.206	1.336	.392	-.336	-.6	-.789	-1.069	-.908
1999	-1.039	-1.123	-.95	-.88	-.596	-.339	-.478	-.739	-.937	-.954	-1.031	-1.142
2000	-1.122	-1.189	-1.09	-.397	.251	.001	-.159	-.145	-.21	-.367	-.701	-.55
2001	-.496	-.649	-.548	-.05	.282	.052	.297	.332	-.147	-.255	-.138	.033
2002	.017	-.16	-.118	.401	.886	.932	.712	1.002	.921	1.02	1.101	1.156
2003	1.214	.944	.83	.413	.214	.107	.177	.309	.492	.534	.584	.362
2004	.332	.37	-.036	.358	.558	.315	.571	.617	.591	.524	.818	.684
2005	.325	.816	1.057	.626	.885	.589	.519	.343	.329	-.152	-.374	-.55
2006	-.428	-.414	-.521	-.571	.045	.526	.716	.748	.84	.976	1.297	.965
2007	.985	.537	.125	.026	.348	-.155	-.248	-.442	-1.175	-1.204	-1.149	-1.178
2008	-1.006	-1.371	-1.552	-.858	-.345	.142	.088	-.269	-.545	-.681	-.584	-.646
2009	-.714	-.69	-.705	-.106	.326	.751	1.06	1.05	.745	.924	1.134	1.059
2010	1.066	1.526	1.462	.978	.658	-.228	-1.103	-1.671	-1.86	-1.888	-1.472	-1.558
2011	-1.719	-1.544	-1.554	-1.387	-.199	-.003	-.193	-.517	-.751	-.917	-.933	-.945
2012	-.98	-.675	-.382	.11	.757	.842	1.126	.607	.351	.097	.141	.111
2013	.103	-.068	-.026	.09	.205	-.094	-.314	-.481	-.125	.148	-.042	-.234
2014	-.27	-.259	.018	.295	1.001	1.046	.915	.937	.593	.45	.773	.566
2015	.417	.464	.614	.916	1.583	2.097	1.981	2.334	2.532	2.256	2.3	2.12
2016	2.216	2.17	1.963	2.094	1.752	1.053	.352	.167	-.091	-.363	-.197	-.11
2017	-.052	-.043	-.08	.744	1.445	1.039	.456	.009	-.449	-.551	-.277	-.576
2018	-.623	-.731	-.502	-.432	.465	.469	.076	.132

(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: 13 October (or earlier) 2018

(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.