The Classic Monsoon Farewell
Traditionally, the monsoon's withdrawal is a gradual and orderly process. It begins in the first half of September from the northwestern state of Rajasthan. As the sun's direct rays move southward, the Indian landmass cools down, and the intense low-pressure
system over the Indo-Gangetic plains weakens. This weakening means it can no longer pull the moisture-laden southwest winds onto the subcontinent. A high-pressure system, known as an anticyclone, starts to form, pushing dry air across the north. This process advances southeastward over several weeks, with the monsoon typically leaving the entire country by mid-October. This withdrawal signals the start of drier, clearer weather, crucial for harvesting summer crops and planting winter ones.
A New, Erratic September
In recent years, this predictable retreat has been replaced by variability. Instead of a steady withdrawal, September now often features intense, short bursts of rainfall, stalls in the retreat process, and delayed departures. As of early September 2026, forecasters noted that while monsoon activity was weakening, active rainfall was still predicted for several states. This follows a pattern where withdrawal has been consecutively delayed for over a decade. These 'active spells' during a supposed withdrawal period can bring unexpected heavy rains, disrupting the transition to the post-monsoon season and creating uncertainty for millions.
Warmer Oceans, More Fuel
A primary driver of this change is climate change, specifically the warming of oceans. The Arabian Sea and the Bay of Bengal, which are warmer than in the past, provide extra moisture and energy to the atmosphere. This increased energy can fuel the formation of low-pressure systems and cyclonic circulations late in the season. Even as the large-scale seasonal wind reversal begins, these powerful, moisture-rich systems can override the retreat process, triggering heavy downpours in central, western, and even northwestern India. A warmer atmosphere can also hold more moisture, which means that when it does rain, the downpours are often more intense than they used to be.
The Influence of Global Patterns
Beyond regional warming, larger climate phenomena like El Niño and the Indian Ocean Dipole (IOD) play a significant role. El Niño, characterized by warmer-than-average sea surface temperatures in the Pacific Ocean, is known to suppress monsoon rainfall and influenced the forecast for a below-normal September in 2026. Conversely, a 'positive' IOD, with warmer waters in the western Indian Ocean, can sometimes counteract El Niño's drying effect and boost late-season rains, as seen in previous years. The interplay between these powerful global patterns can make the monsoon's final month highly unpredictable, either leading to prolonged dry spells or sudden wet ones.
The Ripple Effect on the Ground
This variability is more than just a weather curiosity; it has profound impacts on India's agriculture and water security. Farmers rely on the dry spell in late September to harvest mature kharif crops like rice and soybeans. Unexpected heavy rain can damage standing crops and lead to significant losses. Furthermore, the timing for planting rabi (winter) crops like wheat and chickpeas depends on having the right amount of soil moisture after the monsoon withdraws. A delayed or erratic retreat disrupts this crucial schedule. Water reservoir managers also face a dilemma: whether to release water in anticipation of a dry spell or hold it and risk flooding from a late burst of rain.
