Monsoon 2026: IMD predicts timely May 20 onset in Andaman Sea

📌 Summary:

• India Meteorological Department (IMD) has predicted a "timely" onset of the southwest monsoon over the Andaman Sea around May 20, 2026

• Normal onset date for Andaman Sea: around May 20; this prediction indicates a seasonal onset without any delay

• Southwest monsoon then progressively advances — Kerala onset usually around June 1, followed by rest of India through June-September

• IMD's prediction is based on analysis of sea surface temperatures, wind patterns, and moisture indices in the Indian Ocean and Bay of Bengal region

• India receives about 70–80% of its annual rainfall from the southwest monsoon (June–September); critical for agriculture (kharif crops), groundwater recharge, and reservoir levels

• Good monsoon onset predictions help state governments prepare for flood management, agricultural advisory, and disaster preparedness

🎯 UPSC Relevance: Geography (Prelims) — Monsoon onset sequence, normal dates, and IMD forecasting methods are frequently tested.

📝 Prelims Facts:

• Normal southwest monsoon onset over Andaman Sea: ~May 20

• Normal onset over Kerala: ~June 1

• Southwest monsoon covers all of India by ~July 15

• IMD: India Meteorological Department — under Ministry of Earth Sciences

• Southwest monsoon accounts for ~70–80% of India's annual rainfall

• Monsoon onset is declared when: (a) rainfall ≥2.5mm for 2 consecutive days; (b) OLR <200 W/m²; (c) lower tropospheric winds (850 hPa) are westerly >15 knots

🔑 Key Term: Southwest Monsoon — Seasonal wind system that brings moisture from the Indian Ocean to the Indian subcontinent from June–September; driven by differential heating of land and sea and the Inter-Tropical Convergence Zone (ITCZ).