Southwest Monsoon 2026: Kerala Onset, Branches and UPSC Geography Notes
Context: Southwest Monsoon 2026 to set in over Kerala around June 4
The India Meteorological Department revised the onset of the Southwest Monsoon over Kerala to around 4 June 2026. Kerala is considered the gateway for the monsoon’s arrival over the Indian mainland.
Monsoon: Basics
- Monsoon refers to seasonal reversal of winds due to differential heating of land and sea.
- Southwest Monsoon occurs from June to September.
- It brings nearly 75% of India’s annual rainfall.
- Retreating / Northeast Monsoon occurs from October to December.
- The Northeast Monsoon is important for Tamil Nadu.
Two Branches of Southwest Monsoon
Arabian Sea Branch
- First strikes Kerala.
- Causes heavy rainfall along the Western Ghats.
- Moves towards western and northern India.
Bay of Bengal Branch
- First reaches Northeast India.
- Then moves westward along the Indo-Gangetic Plains.














