Context
IMD projects below-normal monsoon (~92% of LPA) for 2025 due to a developing El Niño, with likely impact in Aug–Sept.
Monsoon and LPA
• Monsoon → seasonal reversal of winds bringing rainfall to India (June–September, ~70% of annual rainfall; peak in July–August)
• LPA (Long Period Average) → average monsoon rainfall over 50 years (1971–2020) used as the benchmark
• 87 cm = 100% rainfall
Classification:
• <90% → Deficient
• 90–96% → Below Normal
• 96–104% → Normal
• >104% → Above Normal
→ 2025: ~92% → Below Normal
Key Terms
- El Niño
→ Periodic warming of central/eastern Pacific Ocean
→ Weakens trade winds and disrupts moisture flow toward India
→ Leads to reduced rainfall, especially in later monsoon months
ENSO
→ Ocean–atmosphere system including El Niño (warm phase) and La Niña (cool phase)
→ Controls global climate variability, including Indian monsoon
