Southwest Monsoon 2025 arrives early over Kerala
Why in the news
The monsoon reached Kerala on May 24, 2025, ahead of the normal June 1 date and the earliest in over a decade (last in 2009).
Key facts
- Southwest monsoon: June to September; vital for farming, drinking water, hydropower.
- IMD onset criteria: 2.5 mm rain for 2 days at 60% of 14 stations; westerlies to 600 hPa with 15-20 knots at 925 hPa; OLR below 200 W/m2.
| Cause of early onset | Role |
|---|---|
| Madden-Julian Oscillation | Boosted convection from May 13 |
| Mascarene High | Moist winds from southern Indian Ocean |
| Somali Jet | Stronger flow towards Kerala |
| Heat low, monsoon trough | Pulled in moisture; triggered rain |
Implications
- Benefits: earlier Kharif sowing, refilled reservoirs, cooler South Indian summer.
- Risks: urban flooding (Bengaluru), uncertain forecasts since early onset does not mean a stronger monsoon.
Exam angle
- Normal Kerala onset: June 1.
- Onset body: IMD.