ICSE Class 10 Geography: Climate of India — Complete Notes 2026

Factors Affecting India's Climate

• Latitude: Tropic of Cancer divides India into tropical and sub-tropical zones
• Altitude: Himalayas — northern plains are warmer in summer than the Himalayan region at same latitude
• Distance from sea: Mumbai has moderate climate; Delhi has extreme continental climate

Indian Monsoon Mechanism

• ITCZ (Inter-Tropical Convergence Zone) migrates north in summer, creates low pressure over Indian subcontinent
• South-West monsoon (June–September): Bay of Bengal branch and Arabian Sea branch; brings 80% of India's rainfall
• Onset: Kerala by June 1; reaches Delhi by end of June; retreats from northwest first

Seasons of India

• Winter (December–February): NE trade winds from land; cold waves in north; mild south
• Summer (March–May): Loo (hot, dry wind) in north; temperatures can reach 45°C in Rajasthan
• SW Monsoon (June–September): retreating monsoon (Oct–Nov) brings rain to southeast coast (Tamil Nadu)

Distribution of Rainfall

• High rainfall (>200 cm): Western Ghats, northeast India (Mawsynram = highest rainfall in world ~11,872 mm)
• Moderate rainfall (75–200 cm): peninsular plateau, Ganga plains
• Low rainfall (<75 cm): Rajasthan, Ladakh, Deccan rain shadow (Pune vs Mumbai contrast)

Monsoon and Indian Economy

• 80% of India's farmers depend on SW monsoon for Kharif crops (rice, cotton, soybean)
• Failure of monsoon → drought; excess rainfall → floods; normal monsoon → GDP boost
• Cyclones form in Bay of Bengal in post-monsoon season; affect Odisha, AP, Tamil Nadu coasts

El Niño Effect

• El Niño: warming of Pacific Ocean surface waters; weakens Indian monsoon → deficit rainfall years
• La Niña: opposite of El Niño; typically strengthens monsoon
• ENSO (El Niño Southern Oscillation): major cause of inter-annual variability in Indian rainfall

ICSE Geography Exam Tips

• Map work: mark annual rainfall distribution, monsoon arrows on India map
• Explain diagrams: ITCZ position in June vs December; monsoon onset map
• Key data to memorize: Mawsynram (highest rainfall), Leh (lowest rainfall), onset dates