Southwest monsoon ends with 12% deficit, October rain also likely below normal: IMD, Pg1

Key Highlights:

• India's 2026 southwest monsoon concluded with 759.4 mm of rainfall, marking a 12.6% deficit compared to the Long Period Average (LPA) of 868.6 mm.
• This rainfall, at 87% of the LPA, represents the lowest recorded southwest monsoon rainfall since 2015.
• The east and northeast region experienced its driest monsoon since 1901, recording 1,017.1 mm of rainfall.
• The subdued rainfall was largely consistent with forecasts by the India Meteorological Department (IMD), which anticipated the impact of a strong El Nino event.

Monsoon Deficit.jpg

Detailed Insights:

• The India Meteorological Department (IMD) had predicted a subdued monsoon since April, with final estimates falling within their forecast range.
• Regional variations were significant, with east and northeast India showing a 25.6% deficit and the southern peninsula a 24.3% deficit.
• The southern peninsula's 542 mm rainfall was its fourth lowest monsoon total since 1901.
• Northwest India and central India recorded deficits of 5.9% and 2.6% respectively, closer to normal.
• Nationally, 17 out of 36 meteorological subdivisions, covering 42% of the country, experienced deficient rainfall.
• The IMD forecasts below-normal rainfall for October, likely less than 85% of the LPA, as the El Nino continues to strengthen.
• The southwest monsoon is in the process of withdrawal, with the northeast monsoon expected to commence in October.

Key Concepts Involved:

• Southwest Monsoon: Seasonal winds bringing the majority of India's annual rainfall from June to September.
• Long Period Average (LPA): A benchmark average of rainfall over a 50-year period, used to classify monsoon performance.
• El Nino: A climate pattern characterized by the unusual warming of surface waters in the equatorial Pacific Ocean, often leading to drier conditions in India.
• India Meteorological Department (IMD): The principal agency responsible for meteorological observations, weather forecasting, and seismology in India.
• Northeast Monsoon: A post-monsoon season, primarily affecting southern peninsular India, bringing rainfall from October to December.