MEI Index (last update: 5 November 2011)
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 -1.046 -1.148 -1.287 -1.058 -1.423 -1.363 -1.342 -1.066 -.576 -.394 -1.168 -1.261
1951 -1.069 -1.194 -1.216 -.434 -.264 .482 .756 .864 .779 .752 .722 .469
1952 .412 .142 .096 .261 -.257 -.633 -.235 -.157 .362 .311 -.343 -.125
1953 .023 .388 .272 .712 .833 .242 .421 .252 .522 .092 .054 .321
1954 -.045 -.019 .169 -.504 -1.397 -1.578 -1.382 -1.467 -1.154 -1.372 -1.144 -1.107
1955 -.762 -.689 -1.132 -1.556 -1.636 -2.276 -1.93 -2.04 -1.826 -1.745 -1.826 -1.867
1956 -1.445 -1.306 -1.399 -1.157 -1.306 -1.516 -1.207 -1.14 -1.363 -1.463 -1.039 -1.032
1957 -.95 -.356 .147 .352 .915 .778 .945 1.128 1.183 1.098 1.13 1.236
1958 1.473 1.447 1.31 1.026 .765 .907 .745 .443 .177 .208 .482 .693
1959 .559 .794 .502 .218 .04 .04 -.179 .074 .055 -.079 -.174 -.258
1960 -.301 -.254 -.081 .02 -.324 -.243 -.345 -.255 -.476 -.365 -.337 -.432
1961 -.161 -.261 -.076 .018 -.29 -.084 -.152 -.237 -.263 -.518 -.43 -.633
1962 -1.081 -.993 -.72 -1.023 -.931 -.857 -.718 -.556 -.55 -.655 -.598 -.484
1963 -.717 -.849 -.706 -.816 -.451 -.038 .456 .63 .763 .83 .853 .737
1964 .859 .453 -.291 -.617 -1.268 -1.094 -1.397 -1.496 -1.286 -1.204 -1.212 -.924
1965 -.541 -.328 -.251 .105 .543 .951 1.399 1.484 1.404 1.219 1.366 1.258
1966 1.314 1.191 .697 .557 -.111 -.11 -.13 .17 -.085 -.014 .021 -.188
1967 -.469 -.936 -1.079 -1.067 -.479 -.364 -.654 -.429 -.632 -.68 -.421 -.376
1968 -.611 -.72 -.63 -.971 -1.06 -.701 -.527 -.121 .24 .425 .59 .348
1969 .674 .863 .447 .617 .706 .8 .419 .142 .158 .505 .652 .385
1970 .36 .406 .217 -.056 -.142 -.74 -1.157 -1.051 -1.245 -1.102 -1.092 -1.233
1971 -1.216 -1.523 -1.811 -1.898 -1.481 -1.511 -1.24 -1.233 -1.463 -1.421 -1.309 -.998
1972 -.587 -.406 -.257 -.205 .498 1.198 1.897 1.822 1.503 1.621 1.731 1.756
1973 1.72 1.491 .85 .481 -.131 -.821 -1.066 -1.369 -1.75 -1.695 -1.516 -1.861
1974 -1.937 -1.797 -1.769 -1.684 -1.09 -.658 -.74 -.628 -.61 -1.049 -1.256 -.922
1975 -.551 -.598 -.874 -.969 -.88 -1.167 -1.491 -1.742 -1.878 -2 -1.786 -1.748
1976 -1.614 -1.394 -1.251 -1.192 -.498 .32 .588 .653 1.027 .953 .474 .551
1977 .516 .261 .098 .531 .346 .501 .852 .691 .817 1.007 .976 .867
1978 .769 .89 .948 .18 -.383 -.546 -.387 -.183 -.386 -.018 .192 .405
1979 .603 .365 -.005 .29 .407 .386 .349 .649 .769 .636 .734 1.006
1980 .682 .585 .668 .872 .913 .851 .791 .341 .278 .205 .239 .1
1981 -.258 -.172 .442 .637 .104 -.023 -.032 -.072 .186 .088 -.051 -.149
1982 -.278 -.154 .081 -.04 .417 .966 1.63 1.829 1.792 2.025 2.451 2.421
1983 2.691 2.908 3.039 2.875 2.548 2.151 1.7 1.114 .422 .002 -.166 -.182
1984 -.335 -.549 .141 .329 .093 -.152 -.152 -.181 -.081 .016 -.348 -.602
1985 -.559 -.597 -.722 -.486 -.743 -.103 -.15 -.395 -.544 -.139 -.057 -.305
1986 -.31 -.203 .02 -.17 .309 .322 .394 .812 1.168 .996 .868 1.183
1987 1.245 1.185 1.718 1.866 2.119 1.91 1.835 1.949 1.832 1.61 1.254 1.267
1988 1.111 .675 .47 .305 .075 -.71 -1.187 -1.382 -1.591 -1.351 -1.468 -1.329
1989 -1.144 -1.297 -1.051 -.844 -.501 -.278 -.468 -.505 -.281 -.318 -.059 .137
1990 .232 .537 .924 .392 .592 .392 .062 .119 .376 .24 .38 .336
1991 .309 .303 .387 .444 .708 1.154 1.005 1.002 .734 1.016 1.203 1.321
1992 1.747 1.87 1.993 2.27 2.138 1.736 .952 .537 .514 .669 .594 .639
1993 .689 .99 .972 1.388 1.976 1.479 1.069 1 .98 1.058 .834 .583
1994 .349 .192 .157 .423 .51 .735 .807 .73 .879 1.434 1.287 1.209
1995 1.211 .957 .853 .419 .503 .464 .177 -.206 -.473 -.488 -.488 -.563
1996 -.641 -.597 -.267 -.506 -.201 .006 -.221 -.401 -.499 -.389 -.157 -.336
1997 -.486 -.607 -.252 .493 1.114 2.308 2.741 3 2.998 2.356 2.531 2.341
1998 2.5 2.788 2.765 2.67 2.148 1.116 .24 -.431 -.674 -.851 -1.153 -.976
1999 -1.109 -1.219 -1.043 -1.026 -.727 -.449 -.5 -.802 -1.009 -1.013 -1.065 -1.196
2000 -1.172 -1.228 -1.117 -.525 .118 -.162 -.219 -.146 -.249 -.382 -.747 -.566
2001 -.514 -.699 -.591 -.149 .151 -.082 .223 .357 -.131 -.276 -.179 .007
2002 -.041 -.206 -.187 .337 .766 .854 .576 .912 .803 .951 1.059 1.123
2003 1.195 .925 .819 .307 .027 .025 .068 .236 .44 .508 .524 .327
2004 .315 .334 -.116 .215 .462 .172 .44 .672 .522 .464 .797 .654
2005 .307 .794 1.017 .558 .735 .487 .476 .307 .251 -.168 -.397 -.586
2006 -.449 -.443 -.581 -.69 -.055 .548 .618 .749 .787 .89 1.308 .976
2007 .997 .526 .082 -.051 .156 -.371 -.334 -.46 -1.169 -1.144 -1.161 -1.146
2008 -.984 -1.389 -1.619 -.945 -.39 .102 -.047 -.286 -.653 -.783 -.59 -.638
2009 -.729 -.705 -.702 -.161 .355 .939 .929 .934 .762 1.018 1.064 1.019
2010 1.148 1.518 1.395 .862 .548 -.466 -1.217 -1.849 -2.037 -1.948 -1.577 -1.552
2011 -1.654 -1.552 -1.548 -1.495 -.368 -.225 -.147 -.503 -.772 -.968
(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: 10 December 2011 (probably 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.