The Telltale Signs of Retreat
The end of the monsoon isn't like flipping a switch. Meteorologically, several conditions must be met. The most crucial is the establishment of an anticyclone—a high-pressure zone—over the lower atmosphere in northwest India. This reverses the moisture-laden
southwesterly winds that define the monsoon, replacing them with dry northwesterlies. For five consecutive days, rainfall must cease over a region, and a visible reduction in moisture must be confirmed via satellite imagery. Recent satellite pictures on September 8th have shown a dramatic reduction in cloud cover over northwest and central India, a strong visual cue that the monsoon's engine is beginning to power down. This widespread clearing is linked to the influence of a powerful El Niño, which is altering circulation patterns and weakening monsoon activity across South Asia.
When Does It Officially Begin?
While the signs are appearing, the official withdrawal has not yet been declared. According to the India Meteorological Department (IMD), the process typically starts from the extreme northwestern parts of the country, like West Rajasthan, around September 17. This year, forecasters suggest conditions will become favourable for this retreat to begin sometime in the second half of September. An anticyclonic circulation, which is key to pushing the monsoon out, is expected to properly establish itself around September 21, setting the stage for a more organized withdrawal. This timeline is crucial, as an earlier or delayed withdrawal has significant implications for the country.
An Erratic Season's Final Act
This year's monsoon has been anything but uniform. The season has been marked by erratic behaviour, with prolonged dry spells followed by intense, short bursts of rain. As of early September, the country as a whole faced a significant rainfall deficit. The IMD has forecast a below-average rainfall for September, coupled with higher-than-normal temperatures, largely due to the strengthening El Niño conditions. While the withdrawal process starts in the northwest, it doesn't mean rain stops everywhere. In fact, IMD forecasts on September 7th predicted continued rainfall in several parts of Northwest, Central, and Northeast India through September 13. This highlights the staggered nature of the withdrawal; while Rajasthan may be drying out, states like Uttarakhand and Assam could still be receiving heavy showers.
What to Expect in Your Region
The monsoon's retreat is a slow, creeping line that moves southeast across the country over several weeks. For North India, the withdrawal ushers in a period of clear skies, lower humidity, and the pleasant onset of autumn. However, for Peninsular India, the story is different. The IMD has noted that subdued rainfall activity is likely to continue over this region for the next week. The complete withdrawal from the entire country, including the southern peninsula, typically happens only after October 1. The moisture from the retreating southwest monsoon can sometimes fuel the northeast monsoon, which brings rain primarily to Tamil Nadu, parts of Andhra Pradesh, and Kerala later in the year. Therefore, the end of the southwest monsoon does not necessarily mean the end of all rain for the southern states.
Impact on Agriculture and Beyond
The timing and intensity of September rains are critical for agriculture. This rainfall is vital for standing summer crops like rice and soybean, which are in their final growth stages. Furthermore, it determines the soil moisture levels for the upcoming Rabi (winter) crop season, when farmers plant wheat, chickpeas, and mustard. A drier-than-normal September, as has been forecast, could stress existing crops and hamper the sowing of winter ones, potentially affecting yields and farm incomes. The transition also marks a shift in daily life, allowing for the start of the festival season in much of the country under clearer skies and paving the way for cooler, more pleasant weather as winter approaches.
