The Mid-Season Slowdown
After a July that brought rainfall figures closer to normal, August has seen a significant downturn, raising anxieties among farmers and policymakers. As of late August, the country-wide seasonal deficit stands at around 13% below the Long Period Average
(LPA). This slowdown is driven by subdued rainfall activity over large parts of the country, particularly the south peninsula. The India Meteorological Department (IMD) had earlier flagged the risk of below-normal rainfall for August and September, primarily due to the strengthening El Niño conditions. The month of August is running a deficit of over 14%, contributing to fears of a weak second half of the season. This dip in performance, while concerning, is not entirely unexpected and fits into a broader pattern of monsoon behaviour.
A Marathon, Not a Sprint
The Southwest Monsoon, which delivers about 70-75% of India's annual rainfall, is best understood as a four-month-long marathon with its own rhythm of active and break periods. It is not a continuous downpour from June to September. This 'intra-seasonal variability' is a core feature of the monsoon system. An active phase sees widespread, vigorous rains, often driven by low-pressure systems moving across the country. A 'break' phase, conversely, is marked by a significant reduction in rainfall over the Indian heartland. This happens when the monsoon trough, an elongated low-pressure zone, shifts northward to the foothills of the Himalayas. This shift starves the plains of rain while simultaneously causing heavy downpours in the Himalayan states and Northeast India. A weak month, therefore, can often be a prolonged 'break' phase within the larger seasonal cycle.
The Global Climate Conductors
The monsoon's performance is heavily influenced by large-scale climate phenomena happening oceans away. The most famous of these is the El Niño-Southern Oscillation (ENSO) in the Pacific Ocean. Currently, moderate El Niño conditions are prevailing and expected to strengthen. Historically, El Niño is associated with suppressed monsoon rainfall in India. The other major player is the Indian Ocean Dipole (IOD), a measure of the sea surface temperature difference between the western and eastern Indian Ocean. A 'positive' IOD, with warmer waters in the west, can counteract El Niño's negative impact and boost the monsoon. However, as of August 2026, the IOD remains neutral, struggling to establish itself against the strong El Niño. The interplay between these two global giants is a primary driver of the year-to-year variation in monsoon strength.
The Pulse Within the Season
While El Niño and the IOD set the background score for the season, the Madden-Julian Oscillation (MJO) directs the weekly tempo. The MJO is a massive, eastward-moving pulse of cloud and rainfall that travels around the tropics every 30 to 60 days. It has an enhanced (wet) phase and a suppressed (dry) phase. When the wet phase of the MJO is over the Indian Ocean, it can trigger active monsoon spells and increase rainfall. Conversely, when its dry phase dominates, it can lead to or prolong monsoon breaks. In August 2026, the MJO has been largely unfavourable, remaining quasi-stationary over the Pacific and contributing to the dry conditions over the Indian peninsula. This demonstrates how these shorter-term oscillations can create significant dry spells even within a broader season.
What September Holds
A weak August doesn't automatically mean a failed monsoon. History has instances where a strong September has compensated for a poor August, pulling the seasonal total back towards normal. The final outcome for 2026 will depend critically on how these interacting factors evolve. The primary concern is the strengthening El Niño, which increases the probability of a below-normal season. Any hope for a late revival hinges on the potential development of a positive IOD and a favourable MJO pulse moving into the Indian Ocean. Forecasters will be watching these signals closely, as September's performance is crucial for the maturation of key kharif crops and for replenishing soil moisture ahead of the rabi planting season.
