Sources & methodology
All data come from official agencies and are downloaded automatically. Every number on this site shows its source and date.
Data sources
Automatic download status for each source.
| Dataset | Publishes | Last checked | Last new data | Status |
|---|---|---|---|---|
NOAA CPC · Public domain (U.S. Government) |
Weekly (Mondays) | 84 min ago | 84 min ago | Up to date |
NOAA CPC · Public domain (U.S. Government) |
Monthly | 83 min ago | 83 min ago | Up to date |
NOAA CPC · Public domain (U.S. Government) |
Monthly | 83 min ago | 83 min ago | Up to date |
NOAA CPC · Public domain (U.S. Government) |
Monthly (2nd Thursday) | 83 min ago | 83 min ago | Up to date |
NOAA PSL · Public domain (U.S. Government) |
Monthly (~10th) | 83 min ago | 83 min ago | Up to date |
IGP / ENFEN (Perú) · Public data, Government of Peru — cite IGP/ENFEN |
Monthly | 71 min ago | 71 min ago | Up to date |
ENFEN (Perú) · Public information, Government of Peru |
About every two weeks | 83 min ago | 83 min ago | Up to date |
NOAA NCEI (via CoastWatch ERDDAP) · Public domain (U.S. Government) |
Daily (~1 day lag) | 79 min ago | never | Up to date |
GDACS (European Commission JRC / UN OCHA) · Free use with attribution to GDACS |
Near real time | 21 min ago | 21 min ago | Up to date |
NOAA NCEI · Public domain (U.S. Government) |
Monthly (~mid-month) | 83 min ago | 83 min ago | Up to date |
Bulletins & further reading
Lower-frequency publications from other forecast centres.
- BoM — Climate Driver Update
- C3S — Copernicus seasonal forecasts
- CIIFEN — Centro Internacional para la Investigación del Fenómeno de El Niño
- FEWS NET — Food security outlooks
- IRI — ENSO Forecast (model plume)
- JMA — El Niño Outlook
- NOAA — ENSO Blog (Climate.gov)
- SENAMHI — Avisos meteorológicos — Perú
- WMO — El Niño / La Niña Updates
Methodology
Indices
Weekly Niño 3.4 and Niño 1+2, ONI, RONI and SOI come from NOAA CPC (1991–2020 base); MEI.v2 from NOAA PSL; ICEN from IGP following ENFEN's 2024 definition. Three-month values are dated at their centre month (e.g. JAS = August). Strength categories use NOAA's usual ONI/RONI thresholds (0.5, 1.0, 1.5 and 2.0 °C) and ENFEN's ICEN thresholds (0.4, 1.0, 1.7 and 3.0 °C).
Sea surface temperature
We use NOAA NCEI's daily OISST v2.1 analysis (preliminary version, ~1 day lag), subsampled to 1° and projected to Mercator. Its anomalies are relative to 1971–2000, so they run slightly higher than CPC's. Daily indices are latitude-weighted means within each region and are unofficial.
Events
Floods, droughts, tropical cyclones and wildfires with an orange or red GDACS alert (European Commission JRC and UN OCHA) are shown. An event matching a typical El Niño impact does not mean El Niño caused it.
Update frequency
The server checks each source at its publishing rhythm: GDACS every 30 minutes, ENFEN and the weekly and daily products every 6 hours, and the monthly indices every 12 hours. Only changed data are processed (ETag/Last-Modified headers and content hashes).