2025 Monsoon Outlook: ENSO Confusion and Forecast Challenges
Why in the news
With the 2025 monsoon approaching, scientists find the Pacific Ocean’s El Nino-La Nina state unusually muddled, complicating forecasts crucial for farming, water and the economy.
Key facts
- Early in 2024, a strong La Nina was expected, backed by cold sea surface temperature (SST) anomalies in the eastern tropical Pacific.
- The cold anomalies then moved west, while warm SST anomalies appeared in the far east; wind patterns were also odd, with easterly and westerly anomalies together.
- The pattern resembles a Dateline El Nino (Central Pacific El Nino): warm SST near the dateline, cold further east. A true La Nina has colder SST from the extreme east to central Pacific and is more predictable.
- Recent studies point to the ENSO Transition Mode (ETM), a natural pattern in the southern Pacific that shapes tropical winds and SST, as the likely disruptor of the expected shift from El Nino (2023-24) to La Nina (2024-25).
Forecast for summer and autumn 2025
| Model view | Outcome |
|---|---|
| Some models | La Nina by autumn |
| Others | A neutral year |
| A few | Possibility of a strong El Nino |
This spread makes accurate monsoon forecasting harder.
Climate complexity
- The ENSO-monsoon link has been changing over recent decades.
- Global warming and mid-latitude meandering of jet streams add variation to monsoon and cyclone patterns; pre-monsoon cyclones can affect onset timing and rainfall.
- Unusual heatwaves in early 2025 add to the challenge; the IMD and global scientists are working to sharpen models.
Exam angle
- Related terms: ENSO, La Nina, El Nino, Dateline El Nino, SST, ETM.
- Agency forecasting the monsoon: India Meteorological Department (IMD).