The Science of a Slow Goodbye
The monsoon's withdrawal isn't an event but a journey that can take over a month. It officially begins when specific meteorological conditions are met over northwest India, including a cessation of rain for five continuous days, a drop in moisture, and
the establishment of an anticyclone in the lower atmosphere. This process typically starts in the northwestern state of Rajasthan. As the landmass cools faster than the ocean, the low-pressure system that pulls moist winds from the sea weakens, causing the winds to reverse. From there, the line of withdrawal slowly moves southeast across the country. This means that on the same day in late September, northern India might be experiencing dry, post-monsoon weather while the southern peninsula is still receiving rain.
North India: Clear Skies and 'September Heat'
For North India, the monsoon's retreat signals the end of persistent humidity and overcast days. The result is often clearer skies, which might sound pleasant but comes with a well-known side effect: the 'September Heat'. With reduced cloud cover, the sun's rays beat down more intensely, causing daytime temperatures to rise significantly. In New Delhi, for example, temperatures can climb back to around 33°C. This period can feel like a short, second summer before the cooler, more pleasant autumn weather sets in. The drop in humidity and cessation of rain are key indicators that the seasonal transition is firmly underway, bringing relief in the evenings even as days remain hot.
South and East: A Different Kind of Retreat
The story is entirely different for the southern and eastern parts of the country. For the southeastern coast, particularly states like Tamil Nadu and parts of Andhra Pradesh, the withdrawal of the Southwest Monsoon paves the way for the Northeast Monsoon. These retreating monsoon winds pick up moisture as they cross the Bay of Bengal, delivering crucial rainfall between October and December. In fact, Tamil Nadu receives a large portion of its annual rainfall during this period. This season can also be associated with the formation of tropical cyclones in the Bay of Bengal, which can bring intense rain and strong winds to the coastal regions.
What to Expect in 2026
The 2026 monsoon season has been marked by erratic behaviour, with an overall rainfall deficit for the country despite some regions experiencing intense downpours and floods. According to the India Meteorological Department (IMD) and other weather models, conditions are becoming favourable for the withdrawal to commence from northwest India in the second half of September. Some forecasts earlier in the year suggested an on-time or even early withdrawal due to prevailing El Niño conditions, which are known to suppress monsoon rainfall. As of early September, subdued rainfall activity has been noted over Peninsular India, while active systems continue to bring rain to parts of central and northwest India. This uneven pattern is expected to define the withdrawal phase, with a potentially patchy and delayed start to the northeast monsoon showers for the southern peninsula.
Impact Beyond the Weather
The timing and nature of the monsoon's retreat have significant consequences beyond daily comfort. For farmers in the north, the remaining soil moisture after the withdrawal is critical for the sowing of winter (Rabi) crops. An early or abrupt end to the rains can pose challenges for agriculture. In the south, the retreating monsoon is vital for filling reservoirs and supporting the agricultural cycle in regions that receive less rain during the main southwest monsoon season. The transition impacts everything from water management and power generation to the simple rhythms of daily life as millions of people across the country adjust to a new season.
