Indian Climate and Monsoon
~11 min read
- Type: Tropical monsoon climate. Hot summer, cool winter, rainy monsoon.
- Southwest monsoon: Onset Kerala 1 June. Branches: Arabian Sea + Bay of Bengal. Withdrawal Sept-Oct.
- NE monsoon: Oct-Dec; brings rain to Tamil Nadu and SE coast.
- Cherrapunji/Mawsynram: World's wettest places (~11,000 mm).
India has a tropical monsoon climate — life and agriculture revolve around the southwest monsoon. NDA tests onset dates, branches, mechanisms (ITCZ, Tibetan plateau, jet stream), and rainfall distribution.
Four Indian Seasons
| Season | Months | Features |
|---|---|---|
| Cold (Winter) | Dec–Feb | NE winds; western disturbances bring snow to Himalayas, light rain to Punjab/Haryana |
| Hot (Summer) | Mar–May | Loo (hot dry wind); pre-monsoon showers (Kalbaisakhi in Bengal, Cherry blossom in Karnataka, Mango showers in Kerala) |
| Southwest Monsoon | Jun–Sep | ~75% of annual rainfall; arrives Kerala 1 June, covers all India by mid-July |
| Retreating Monsoon (NE) | Oct–Nov | October heat → NE monsoon brings rain to TN, Andhra coast, S Karnataka |
The Southwest Monsoon
Mechanism:
- Intense summer heating of the Indian subcontinent creates low pressure over north-west India.
- The Inter-Tropical Convergence Zone (ITCZ) shifts to ~25° N in summer.
- Cross-equatorial flow draws moisture-laden SE trade winds from the southern Indian Ocean, which on crossing the equator become SW winds.
- Tibetan plateau heating creates an upper-level easterly jet, strengthening the monsoon.
Two branches:
- Arabian Sea branch: Hits Western Ghats → heavy rain on Konkan-Malabar coast; rain shadow on Deccan plateau.
- Bay of Bengal branch: Hits NE hills → Cherrapunji and Mawsynram (Meghalaya), wettest places on Earth.
Northeast Monsoon
Oct-Dec. As ITCZ retreats south and pressure reverses, winds blow from land to sea. Crossing the Bay of Bengal, they pick up moisture and drop it on Tamil Nadu, southeastern Andhra Pradesh and southern Karnataka. Tamil Nadu gets ~60% of its annual rainfall from the NE monsoon.
Rainfall Distribution
| Region | Annual rainfall |
|---|---|
| Mawsynram, Cherrapunji (Meghalaya) | > 11,000 mm — world's wettest |
| Western Ghats (windward, e.g., Mahabaleshwar) | 2,000–4,000 mm |
| Northeast India, Himalayan foothills | 2,000–3,000 mm |
| Ganga Plains (UP, Bihar) | 1,000–1,500 mm |
| Tamil Nadu (NE monsoon belt) | 800–1,200 mm |
| Deccan interior (Maharashtra, Karnataka) | 600–1,000 mm (rain shadow of Western Ghats) |
| Rajasthan, Punjab interior | 200–500 mm |
| Western Rajasthan (Thar) | < 150 mm (driest) |
NDA PYQ Examples
Q: The SW monsoon usually arrives in Kerala around:
(a) 15 May (b) 1 June (c) 15 June (d) 1 July
Answer: (b) 1 June.
Q: Which place receives the highest rainfall in India?
(a) Cherrapunji (b) Mawsynram (c) Mahabaleshwar (d) Agumbe
Answer: (b) Mawsynram (Meghalaya) — has overtaken Cherrapunji.
Q: Tamil Nadu gets most of its rain from:
(a) SW monsoon (b) Western disturbances (c) NE (retreating) monsoon (d) Convectional storms
Answer: (c) NE monsoon — Oct-Dec.
Q: The Deccan Plateau gets less rainfall because it is in the:
(a) Trade wind belt (b) Rain shadow of Western Ghats (c) Sub-polar low (d) Polar high
Answer: (b) Rain shadow of Western Ghats.
Drill Indian Climate and Monsoon for NDA
NDA-pattern items on Indian Climate and Monsoon with answer keys and explanations.
Start Free Mock TestFrequently Asked Questions
What causes the Indian monsoon?
Differential heating of land vs sea. India's land heats faster than the surrounding ocean in summer, creating low pressure that pulls moist sea winds inland. The 23.5° axial tilt drives the ITCZ northward in summer. Tibet's high plateau adds heating that boosts the system.
What is the difference between SW and NE monsoon?
SW monsoon (Jun-Sep) brings 75% of India's rain; arrives from the Arabian Sea and Bay of Bengal; major rain. NE monsoon (Oct-Dec) is a retreating wind that brings rain mostly to Tamil Nadu and SE coast.
What is a western disturbance?
An extra-tropical low pressure system that originates over the Mediterranean and travels eastward, reaching India in winter. Brings rain to Punjab and snow to the Himalayas — important for rabi crops.
Why does the monsoon fail?
Most often due to El Nino — Pacific warming weakens the cross-equatorial flow. Also: weak Tibetan heating, poor northward ITCZ shift, late onset.
Why are Bay of Bengal and Arabian Sea monsoon branches different?
Bay of Bengal branch travels over warmer waters and is deflected by NE hills → very heavy rain. Arabian Sea branch hits Western Ghats first and exhausts moisture there → rain shadow east of the Ghats.