An Official, Yet Erratic, Farewell
The end of the southwest monsoon isn't like flipping a switch. It is a staggered withdrawal that typically begins from the northwestern parts of the country and moves southeast over five to six weeks. According to the India Meteorological Department (IMD),
conditions become favourable for withdrawal when rainfall ceases over an area for five continuous days and an anticyclonic circulation is established in the lower atmosphere. While satellite images on September 8th showed significantly reduced cloud cover, suggesting weakening monsoon activity, the formal withdrawal has not been officially declared but is expected to commence around the middle of the month. This year's monsoon has been notably erratic, with the country facing an overall rainfall deficit even as some regions experienced intense downpours and floods.
Shifting Weather Across the North
For North and Northwest India, the retreat signals the onset of drier days. Strong northwesterly winds are expected to sweep across the region, cutting off the moisture supply that fuels monsoon rains. This will lead to clearer skies and a rise in daytime temperatures. While rainfall has been active over states like Himachal Pradesh and Uttarakhand in early September, the withdrawal will bring this to a definitive end. The establishment of a 'monsoon withdrawal anticyclone' over this region marks a clear shift in the weather pattern, ushering in a post-monsoon phase characterized by dry and sunny conditions. Farmers in the plains will be closely watching soil moisture levels as they prepare for the sowing of rabi (winter) crops.
The Second Coming: Northeast Monsoon
While the southwest monsoon says goodbye, Peninsular India, particularly the southeastern coast, prepares for a different rainy season: the northeast monsoon. This system, also known as the 'retreating monsoon', is critical for Tamil Nadu, coastal Andhra Pradesh, and parts of Karnataka, bringing them significant rainfall between October and December. After a particularly hot and dry August, meteorologists are hopeful for a stronger northeast monsoon this year, which is crucial for replenishing reservoirs and groundwater in the region. However, the erratic nature of the main monsoon and the influence of a strong El Niño could make its arrival and performance patchy.
Cyclone Season Approaches
The post-monsoon period, from October to December, is also the primary season for cyclonic activity in the Bay of Bengal and the Arabian Sea. As the southwest monsoon winds retreat, the large-scale atmospheric conditions change, creating a more favourable environment for the formation of tropical cyclones. These systems can bring intense rainfall and high-velocity winds, primarily affecting the coastal states of Odisha, West Bengal, Andhra Pradesh, and Tamil Nadu on the east coast, and Gujarat and Maharashtra on the west. While early forecasts for September suggest a low to moderate probability of cyclogenesis, vigilance is key during these months. The IMD continuously monitors the seas for any developing systems to provide timely warnings.
The Final Tally: Deficits and Disparities
This year's monsoon season has been a story of contrasts. As of early September, the country as a whole registered a significant rainfall deficit. The South Peninsula and East and Northeast India were particularly dry, with deficits well below normal levels. At the same time, isolated areas in other regions experienced extreme rainfall events, causing flooding and landslides. This uneven distribution is a growing trend, attributed by experts to climate change and phenomena like El Niño, which can weaken the overall monsoon while increasing the frequency of intense downpours. The final performance of the monsoon will have lasting effects on agricultural output, water reservoir levels, and the rural economy as the country transitions into a new weather season.
