MEI Index (last update: 3 February 2015)

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	-1.027	-1.143	-1.29	-1.061	-1.416	-1.372	-1.332	-1.061	-.584	-.402	-1.157	-1.25
1951	-1.071	-1.193	-1.208	-.439	-.305	.438	.715	.847	.769	.743	.722	.466
1952	.403	.135	.086	.257	-.289	-.657	-.255	-.174	.357	.304	-.347	-.129
1953	.016	.382	.263	.711	.83	.227	.395	.248	.52	.091	.048	.311
1954	-.054	-.017	.178	-.51	-1.433	-1.585	-1.402	-1.467	-1.157	-1.374	-1.144	-1.106
1955	-.772	-.695	-1.134	-1.56	-1.631	-2.291	-1.953	-2.05	-1.831	-1.748	-1.834	-1.863
1956	-1.439	-1.297	-1.396	-1.158	-1.309	-1.513	-1.208	-1.134	-1.364	-1.464	-1.041	-1.021
1957	-.949	-.35	.156	.351	.901	.768	.924	1.122	1.179	1.097	1.129	1.231
1958	1.472	1.451	1.317	1.025	.724	.893	.711	.428	.178	.208	.486	.707
1959	.578	.804	.502	.218	.001	.01	-.187	.069	.055	-.082	-.18	-.263
1960	-.31	-.26	-.08	.017	-.334	-.247	-.361	-.254	-.476	-.364	-.338	-.432
1961	-.152	-.267	-.082	.017	-.289	-.098	-.175	-.242	-.268	-.513	-.435	-.643
1962	-1.091	-.99	-.715	-1.023	-.902	-.855	-.711	-.545	-.547	-.657	-.6	-.48
1963	-.7	-.838	-.696	-.814	-.477	-.052	.445	.626	.764	.832	.859	.748
1964	.855	.448	-.294	-.616	-1.275	-1.096	-1.411	-1.5	-1.291	-1.209	-1.202	-.913
1965	-.526	-.323	-.249	.102	.521	.944	1.391	1.477	1.405	1.22	1.367	1.256
1966	1.308	1.192	.697	.555	-.146	-.134	-.153	.165	-.091	-.015	.026	-.181
1967	-.473	-.94	-1.079	-1.066	-.469	-.315	-.606	-.427	-.634	-.679	-.421	-.366
1968	-.593	-.703	-.613	-.971	-1.097	-.748	-.55	-.121	.233	.425	.603	.359
1969	.69	.866	.445	.617	.697	.799	.426	.158	.161	.504	.653	.383
1970	.361	.405	.215	-.055	-.13	-.72	-1.137	-1.042	-1.245	-1.103	-1.09	-1.248
1971	-1.224	-1.521	-1.811	-1.896	-1.449	-1.485	-1.222	-1.234	-1.462	-1.421	-1.313	-1.011
1972	-.594	-.408	-.253	-.205	.478	1.166	1.896	1.823	1.512	1.626	1.722	1.745
1973	1.704	1.482	.841	.481	-.129	-.815	-1.072	-1.37	-1.743	-1.692	-1.519	-1.87
1974	-1.942	-1.794	-1.765	-1.682	-1.073	-.642	-.723	-.629	-.617	-1.05	-1.255	-.931
1975	-.566	-.606	-.882	-.969	-.852	-1.145	-1.477	-1.731	-1.874	-2	-1.793	-1.757
1976	-1.625	-1.399	-1.255	-1.191	-.477	.343	.617	.668	1.024	.947	.48	.552
1977	.518	.254	.091	.531	.331	.483	.859	.689	.812	1.006	.974	.879
1978	.779	.896	.955	.181	-.389	-.568	-.407	-.193	-.386	-.023	.197	.399
1979	.596	.361	-.011	.289	.384	.389	.355	.644	.769	.64	.737	1.016
1980	.698	.594	.669	.875	.922	.855	.782	.341	.284	.208	.238	.118
1981	-.243	-.165	.443	.638	.125	-.023	-.033	-.082	.179	.091	-.051	-.148
1982	-.278	-.15	.086	-.038	.407	.954	1.626	1.827	1.797	2.021	2.447	2.411
1983	2.687	2.909	3.038	2.873	2.561	2.18	1.738	1.137	.439	.003	-.171	-.172
1984	-.338	-.564	.131	.33	.144	-.107	-.129	-.185	-.084	.017	-.348	-.611
1985	-.557	-.603	-.737	-.483	-.716	-.09	-.146	-.398	-.537	-.139	-.053	-.289
1986	-.302	-.194	.033	-.166	.322	.316	.389	.811	1.157	.994	.867	1.181
1987	1.237	1.183	1.724	1.866	2.131	1.923	1.841	1.956	1.84	1.612	1.252	1.253
1988	1.093	.664	.456	.308	.103	-.682	-1.164	-1.378	-1.574	-1.342	-1.463	-1.339
1989	-1.165	-1.312	-1.056	-.84	-.459	-.256	-.448	-.494	-.28	-.312	-.061	.145
1990	.234	.529	.916	.397	.614	.43	.093	.126	.376	.247	.378	.339
1991	.312	.306	.393	.445	.718	1.14	1.009	1.01	.738	1.02	1.203	1.318
1992	1.749	1.872	1.992	2.271	2.141	1.74	.953	.536	.508	.672	.603	.642
1993	.701	.998	.979	1.39	1.992	1.499	1.096	1.006	.987	1.06	.826	.565
1994	.34	.191	.159	.426	.531	.764	.835	.742	.886	1.434	1.28	1.184
1995	1.198	.959	.862	.421	.508	.465	.178	-.198	-.456	-.478	-.486	-.553
1996	-.64	-.599	-.264	-.501	-.14	.022	-.21	-.399	-.495	-.381	-.155	-.337
1997	-.485	-.611	-.254	.497	1.121	2.314	2.764	3.004	3.005	2.363	2.527	2.326
1998	2.481	2.78	2.748	2.672	2.178	1.165	.284	-.417	-.655	-.844	-1.165	-1.01
1999	-1.151	-1.237	-1.068	-1.023	-.664	-.403	-.469	-.779	-.997	-1.007	-1.072	-1.205
2000	-1.195	-1.246	-1.138	-.521	.188	-.101	-.187	-.143	-.243	-.381	-.75	-.582
2001	-.539	-.718	-.607	-.145	.22	-.028	.267	.364	-.124	-.273	-.176	.005
2002	-.049	-.213	-.201	.342	.801	.882	.613	.928	.813	.955	1.063	1.114
2003	1.185	.923	.82	.311	.07	.048	.093	.246	.442	.515	.528	.319
2004	.31	.327	-.125	.221	.495	.223	.478	.671	.526	.476	.795	.647
2005	.302	.795	1.018	.562	.782	.504	.492	.319	.262	-.164	-.4	-.583
2006	-.469	-.457	-.591	-.686	-.018	.565	.637	.76	.802	.899	1.299	.953
2007	.972	.509	.074	-.047	.213	-.3	-.294	-.448	-1.152	-1.133	-1.165	-1.164
2008	-1.009	-1.403	-1.635	-.942	-.348	.14	.011	-.262	-.631	-.77	-.605	-.66
2009	-.752	-.72	-.719	-.157	.375	.934	.949	.957	.77	1.025	1.066	1.013
2010	1.153	1.517	1.386	.867	.609	-.388	-1.17	-1.808	-2.019	-1.943	-1.588	-1.574
2011	-1.677	-1.565	-1.562	-1.488	-.281	-.136	-.076	-.462	-.753	-.956	-.965	-.976
2012	-1.045	-.705	-.417	.061	.73	.909	1.138	.575	.278	.112	.176	.041
2013	.041	-.165	-.171	.01	.108	-.242	-.436	-.586	-.175	.102	-.08	-.3
2014	-.312	-.269	-.017	.152	.932	.878	.816	.858	.5	.36	.712	.578
2015	.406

(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: 7 March 2015 (or earlier)

(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.