MEI Index (last update: 10 May 2013)
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 -1.022 -1.146 -1.289 -1.058 -1.42 -1.366 -1.33 -1.065 -.581 -.395 -1.152 -1.247
1951 -1.068 -1.196 -1.208 -.437 -.275 .464 .739 .853 .774 .751 .727 .467
1952 .406 .131 .086 .262 -.267 -.638 -.245 -.16 .362 .31 -.34 -.126
1953 .024 .379 .263 .712 .84 .246 .416 .253 .521 .093 .048 .312
1954 -.051 -.018 .178 -.506 -1.425 -1.589 -1.397 -1.468 -1.156 -1.372 -1.145 -1.106
1955 -.771 -.697 -1.134 -1.557 -1.631 -2.287 -1.932 -2.043 -1.825 -1.745 -1.827 -1.862
1956 -1.436 -1.3 -1.396 -1.156 -1.302 -1.508 -1.207 -1.143 -1.364 -1.462 -1.036 -1.015
1957 -.948 -.35 .156 .352 .908 .773 .937 1.122 1.183 1.098 1.132 1.231
1958 1.473 1.45 1.317 1.025 .743 .896 .708 .433 .176 .208 .49 .707
1959 .574 .804 .502 .217 .016 .022 -.2 .072 .054 -.08 -.184 -.265
1960 -.311 -.262 -.08 .019 -.325 -.242 -.349 -.252 -.474 -.364 -.339 -.433
1961 -.152 -.267 -.082 .018 -.284 -.083 -.178 -.248 -.263 -.518 -.44 -.644
1962 -1.093 -.992 -.715 -1.023 -.92 -.857 -.712 -.55 -.549 -.656 -.595 -.478
1963 -.703 -.838 -.696 -.816 -.469 -.044 .438 .628 .762 .83 .856 .748
1964 .857 .447 -.294 -.617 -1.273 -1.097 -1.406 -1.503 -1.287 -1.206 -1.195 -.905
1965 -.525 -.323 -.249 .104 .535 .956 1.395 1.483 1.404 1.22 1.369 1.257
1966 1.311 1.191 .697 .556 -.135 -.128 -.149 .164 -.088 -.014 .025 -.181
1967 -.473 -.939 -1.079 -1.067 -.478 -.354 -.63 -.431 -.633 -.681 -.424 -.368
1968 -.595 -.7 -.613 -.973 -1.095 -.731 -.55 -.128 .235 .424 .6 .36
1969 .688 .868 .445 .617 .706 .798 .421 .145 .157 .506 .646 .38
1970 .359 .407 .215 -.055 -.133 -.736 -1.14 -1.043 -1.246 -1.102 -1.095 -1.249
1971 -1.224 -1.521 -1.811 -1.897 -1.461 -1.5 -1.225 -1.234 -1.463 -1.421 -1.306 -1.006
1972 -.592 -.41 -.253 -.206 .487 1.193 1.886 1.823 1.506 1.623 1.724 1.748
1973 1.707 1.481 .841 .482 -.124 -.819 -1.068 -1.368 -1.747 -1.694 -1.524 -1.873
1974 -1.942 -1.792 -1.765 -1.684 -1.081 -.647 -.727 -.633 -.613 -1.049 -1.255 -.93
1975 -.564 -.606 -.882 -.967 -.853 -1.149 -1.478 -1.734 -1.874 -1.999 -1.794 -1.758
1976 -1.624 -1.398 -1.255 -1.191 -.481 .342 .613 .66 1.027 .952 .482 .555
1977 .517 .254 .091 .531 .342 .503 .868 .703 .816 1.007 .973 .877
1978 .779 .897 .955 .18 -.396 -.563 -.412 -.186 -.386 -.019 .198 .398
1979 .595 .36 -.011 .29 .397 .387 .358 .642 .768 .637 .733 1.014
1980 .695 .597 .669 .872 .918 .851 .787 .34 .279 .206 .236 .118
1981 -.245 -.162 .443 .637 .12 -.018 -.034 -.073 .184 .089 -.054 -.153
1982 -.282 -.146 .086 -.041 .407 .951 1.62 1.825 1.794 2.024 2.454 2.413
1983 2.688 2.904 3.039 2.876 2.556 2.174 1.741 1.13 .428 .002 -.176 -.176
1984 -.339 -.565 .131 .331 .124 -.127 -.138 -.179 -.082 .016 -.351 -.611
1985 -.561 -.602 -.737 -.484 -.73 -.094 -.156 -.392 -.541 -.14 -.05 -.293
1986 -.307 -.191 .033 -.169 .305 .311 .384 .804 1.166 .996 .872 1.183
1987 1.237 1.185 1.724 1.865 2.122 1.91 1.847 1.951 1.835 1.61 1.253 1.251
1988 1.092 .665 .456 .307 .088 -.697 -1.174 -1.374 -1.586 -1.35 -1.468 -1.343
1989 -1.166 -1.312 -1.056 -.842 -.487 -.266 -.454 -.501 -.28 -.318 -.066 .142
1990 .234 .532 .916 .393 .595 .408 .084 .123 .376 .241 .372 .335
1991 .309 .31 .393 .444 .719 1.154 1.011 1.012 .737 1.017 1.202 1.32
1992 1.75 1.871 1.992 2.271 2.13 1.722 .946 .536 .512 .669 .602 .644
1993 .699 .999 .979 1.388 1.987 1.478 1.09 1.003 .982 1.059 .822 .562
1994 .338 .192 .159 .423 .522 .747 .823 .743 .88 1.433 1.278 1.184
1995 1.2 .961 .862 .419 .495 .463 .182 -.197 -.468 -.487 -.495 -.559
1996 -.644 -.595 -.264 -.505 -.174 .011 -.208 -.396 -.499 -.387 -.161 -.338
1997 -.487 -.607 -.254 .493 1.119 2.307 2.756 3.001 3 2.358 2.518 2.32
1998 2.483 2.777 2.748 2.673 2.171 1.151 .285 -.41 -.667 -.849 -1.17 -1.012
1999 -1.149 -1.238 -1.068 -1.022 -.678 -.412 -.465 -.787 -1.004 -1.011 -1.079 -1.207
2000 -1.197 -1.246 -1.138 -.521 .161 -.129 -.201 -.14 -.247 -.381 -.755 -.581
2001 -.539 -.717 -.607 -.146 .188 -.056 .253 .367 -.126 -.276 -.18 .003
2002 -.05 -.21 -.201 .339 .78 .864 .596 .922 .808 .952 1.059 1.11
2003 1.184 .927 .819 .308 .05 .033 .089 .241 .441 .509 .519 .315
2004 .308 .33 -.125 .216 .472 .19 .472 .669 .524 .467 .786 .643
2005 .301 .799 1.018 .559 .758 .499 .492 .321 .255 -.166 -.407 -.585
2006 -.471 -.455 -.591 -.688 -.034 .564 .628 .759 .793 .892 1.292 .951
2007 .974 .51 .074 -.049 .187 -.331 -.29 -.44 -1.162 -1.142 -1.177 -1.168
2008 -1.011 -1.402 -1.635 -.942 -.353 .136 .003 -.266 -.643 -.78 -.621 -.666
2009 -.752 -.719 -.719 -.159 .37 .943 .938 .944 .764 1.02 1.062 1.008
2010 1.153 1.52 1.386 .863 .577 -.433 -1.166 -1.822 -2.03 -1.946 -1.602 -1.579
2011 -1.678 -1.562 -1.562 -1.492 -.322 -.169 -.087 -.472 -.764 -.965 -.978 -.978
2012 -1.045 -.706 -.417 .058 .706 .903 1.139 .579 .271 .103 .166 .037
2013 .042 -.163 -.171 .009
(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 June 2013 (apologies for the delay, I will be on travel)
(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.