Limp monsoon that left swathes of India bone dry | Number Theory

Wednesday marked the end of the four-month-long southwest monsoon, which normally accounts for 75% of India’s annual rainfall.

Wednesday marked the end of the four-month-long southwest monsoon, which normally accounts for 75% of India’s annual rainfall. How was the rainfall performance this season? Bad is the short answer, with total monsoon rainfall being the 17th lowest since 1901 (earliest available data). This detailed analysis explains exactly what this entails.

Total monsoon rainfall received is the 17th lowest since 1901 (earliest available data) (Unsplash)

• A month of surplus rain did not ease the El Nino pain

  An early El Nino—a cyclical warming of the central eastern equatorial Pacific Ocean that crimps monsoon rain—meant that rainfall would be underwhelming. According to the India Meteorological Department’s (IMD) real-time gridded data, India received 767mm rainfall this monsoon in terms of area weighted average. This is the 17th lowest monsoon rainfall for since 1901 and 10.5% below the 1971-2020 average for the same period, which IMD currently considers as the Long Period Average (LPA) for tracking monsoon rain. This also makes the 2026 monsoon the driest since 2009, when India got 722mm rain by weighted average. Only July recorded a surplus this monsoon, although the deficit was relatively small in September too. To be sure, IMD’s published statistics may show slightly different numbers because they use a somewhat different method for computing India averages.
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  39% of the country’s area has drought-like conditions

  There is no uniform definition of drought in India. This is because the term has practical implications for agriculture, and vegetation stress is not guided by rainfall alone. One rainfall-based definition sometimes used in Mausam (the quarterly research journal of IMD) defines a 26%-50% rainfall deficit over LPA as a “moderate” drought and more than 50% deficit as a “severe” drought. The gridded data shows that 39% of the country is in drought, with 11.7% in the severe range. The area under drought is the 17th highest since 1901 and the area under severe drought is the 25th highest.
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  Long dry spells were the norm in western and peninsular India

  This can be seen by tracking dry days or days of rain under 2.5mm. Parts of Tamil Nadu, Andhra Pradesh, Karnataka, Maharashtra, Gujarat, and Rajasthan saw the longest dry spell – consecutive dry days – stretch longer than 50 days. At least half of the area of most states also saw more dry days this monsoon than in the 1971-2020 average. The only exceptions were Uttar Pradesh, West Bengal, and Madhya Pradesh among big states, and even here, 39%-48% of the area saw more dry days than normal.
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  Low-pressure systems kept parts of eastern and central India wet

  While a drought-like dryness leads to water stress, it does not mean agriculture will be completely doomed. Some parts, such as the Indo-Gangetic plains, are well-irrigated. On the other hand, parts of these plains faced floods. IMD defines a surplus of 20%-59% as “excess” and of at least 60% as “large excess”. Deficits of the same degree are called “deficient” and “large deficient”, with deviation up to ±19% of LPA called “normal”. 52.7% of the country ended up in the normal and excess categories for June-September. But that was because of monsoon low-pressure systems that travelled from the Bay of Bengal to bring excess rain in the July-September period. Odisha and parts of Chhattisgarh, Madhya Pradesh, and Uttar Pradesh were the most affected by storms of this kind. Another peculiarity this monsoon was the flooding in Bihar, though most of the state was deficient even from July to September. This was because of floods in rivers and tributaries that flow to the state either from Nepal or its neighbouring states. This means crop damage and likely headwinds to farm incomes and tailwinds to inflation not just on account of low rain but also more rain than what was needed.