Monsoon retreats as October heat looms

• The Southwest Monsoon begins its retreat across India in October.
• IMD expects the withdrawal to finish in most areas by mid-month.
• Most regions will be drier, though the South awaits Northeast rains.

As September gives way to October, a significant shift occurs in India's weather. The four-month-long Southwest Monsoon begins its retreat, ushering in a period of transition that dramatically alters rainfall and temperature patterns across the subcontinent.

The Great Monsoon Retreat

October is defined by the withdrawal of the Southwest Monsoon, a process that doesn't happen overnight. It's a gradual retreat that starts in early September from the northwestern parts of the country, like Rajasthan. According to the India Meteorological Department (IMD), this process is declared based on specific criteria, including a cessation of rainfall for five continuous days and a change in wind patterns. By the beginning of October, the monsoon has typically withdrawn from the northern plains. For 2026, the withdrawal began from west Rajasthan around September 19 and has progressed through Punjab, Haryana, and Delhi. The IMD expects the withdrawal to be complete from most parts of the country by the middle of the month, paving the way for a new weather regime.

A Tale of Two Monsoons

While the Southwest Monsoon says goodbye, parts of Southern India prepare to welcome the Northeast Monsoon, also known as the 'retreating monsoon'. This system is crucial for the southeastern parts of the country, particularly Tamil Nadu and Puducherry, which receive a significant portion of their annual rainfall during this period from October to December. The IMD has forecast that the onset of the Northeast Monsoon for 2026 is likely to occur between October 15 and 21. For the October-December period, rainfall is expected to be normal for the southern peninsula as a whole. However, for most other parts of India, October is likely to be drier than usual. The IMD has forecast below-normal rainfall for the country as a whole for the month.

The Notorious 'October Heat'

Before winter coolness sets in, many parts of India, especially the northern and western plains, experience a phenomenon known as 'October Heat'. As the monsoon retreats, the cloud cover disappears, leading to clear skies and a sharp increase in daytime temperatures. This rise in temperature, combined with the high humidity left behind by the monsoon, creates an oppressive and uncomfortable climate. The land is still moist, and when the sun beats down, the high moisture content in the air prevents sweat from evaporating easily, making it feel much hotter than the actual temperature. This period of hot and humid weather is a classic feature of the post-monsoon transition.

A Regional Temperature Rundown

Temperature patterns in October show significant regional variation. In North India, as the monsoon withdraws, days become sunny and warm while nights start to get pleasantly cool. Maximum temperatures in Delhi, for example, are expected to hover between 33 and 35 degrees Celsius in early October. In Central and Western India, the weather becomes generally dry and pleasant, with average highs around 30-32 degrees Celsius, though some areas like Mumbai can experience intense October heat. The east coast, around Chennai and Kolkata, sees temperatures ranging from 26°C to 32°C, but with the lingering possibility of rain. The west coast, including Goa and Kerala, remains warm, with temperatures typically between 25°C and 32°C. Overall, October marks the end of the rains for most and the start of a more comfortable, tourist-friendly season.