Indian Climate & Monsoon

📖 The four seasons of India

• Winter (December-February) — cool, dry conditions in most of the country; some winter rainfall in the northwest from "Western Disturbances."
• Summer / Pre-monsoon (March-May) — high temperatures, especially in the interior; "Loo" hot winds in North India.
• Southwest Monsoon (June-September) — the main rainy season, contributing roughly 75% of India's annual rainfall.
• Post-monsoon / Retreating Monsoon (October-November) — monsoon withdrawal, brings rainfall to the southeastern coast (Tamil Nadu) via the Northeast Monsoon.

🌬️ Mechanism of the Southwest Monsoon

The monsoon arises from differential heating between the Indian landmass (heats up faster in summer) and the surrounding Indian Ocean, creating a low-pressure zone over land that draws in moisture-laden winds from the sea. The monsoon typically arrives at the Kerala coast around 1 June and gradually advances across the country.

🗺️ Regional variation

Rainfall is highly uneven — areas like Mawsynram and Cherrapunji in Meghalaya receive some of the highest rainfall in the world due to orographic effects (moist winds forced upward by the hills), while regions like western Rajasthan remain arid, lying in the "rain shadow" or receiving winds that have already lost most of their moisture.