The Withdrawal Has Begun, Unofficially
As of early September, satellite images show India with strikingly reduced cloud cover, particularly over the northwest and central parts of the country. While this signals a weakening of monsoon activity, the India Meteorological Department (IMD) has
not yet officially declared the start of the withdrawal. The formal process, which has specific meteorological criteria, is expected to commence after September 15, starting from west Rajasthan and progressing southeastward over several weeks. This year's withdrawal is unfolding against the backdrop of a rainfall deficit, with the season's rainfall being below normal due to a strong El Niño effect.
Say Goodbye to Widespread Rains
The most obvious change is the cessation of widespread, persistent rainfall. The retreat begins when rainfall activity stops over an area for five consecutive days, an anticyclone forms in the lower atmosphere, and moisture levels drop significantly. While some regions, like parts of central and northwest India, may still see fairly widespread rains until mid-September, the overall trend is toward drier conditions. Peninsular India, in particular, is expected to see subdued rainfall activity as the monsoon system weakens. This gradual drying out is the first and most definitive sign that the season is turning.
Brace for the 'Second Summer'
As the monsoon clouds disappear, the sun's rays beat down with renewed intensity. This, combined with the high moisture left in the soil and atmosphere from months of rain, creates a phenomenon known as 'October Heat'. This period is marked by a rise in daytime temperatures and oppressive humidity, a combination that often feels more uncomfortable than the dry heat of May and June. While the nights may become cooler and more pleasant, the days can be particularly sultry. This phase acts as a transition between the hot, rainy season and the cool, dry winter, typically lasting from early October to mid-November.
Shifting Winds and Clearer Skies
The entire monsoon is driven by a seasonal shift in wind direction. The retreat is no different. The low-pressure trough that sits over the northern plains during the monsoon weakens and is replaced by a high-pressure system. This causes the moisture-laden south-westerly winds to retreat and eventually be replaced by drier north-easterly winds, which are characteristic of the post-monsoon and winter seasons. The immediate effect for most people will be the return of clear blue skies, a welcome sight after months of grey cloud cover.
The Post-Monsoon Cyclone Season
While the southwest monsoon winds recede, the weather doesn't necessarily become quiet everywhere. The post-monsoon period, from October to December, is one of two major cyclone seasons in the North Indian Ocean, particularly for the Bay of Bengal. These post-monsoon cyclones can sometimes be more intense and destructive. With the main monsoon circulation gone, conditions can become favorable for the formation of powerful cyclonic storms that primarily threaten the eastern coast. It's a critical time for disaster preparedness in coastal states.
