Explained: Why Mumbai is seeing a rainy start to October

**Next Article Explained: Why Mumbai is Seeing a Rainy Start to October**
*By Snehil Singh | Oct 06, 2025, 04:53 PM*

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**What’s the story?**

Mumbai experienced its earliest monsoon onset in 75 years on May 26. Despite October starting, the city continues to receive more rainfall than usual. The India Meteorological Department (IMD) has forecast another spell of rain beginning Monday, further delaying the monsoon’s withdrawal from the city.

Typically, the southwest monsoon begins to withdraw around October 8, but this year, the retreat appears to be postponed once again.

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**Weather patterns: What is causing unseasonal rains?**

The persistent rain activity in Mumbai is attributed to an approaching western disturbance. This weather system, which typically brings rain to northern India during winter, originates near the Mediterranean region. It travels eastward across Afghanistan and Iran after gathering moisture from the Mediterranean, Black, Caspian, and Arabian Seas.

In Mumbai, this disturbance has intensified the monsoon trough—a long, low-pressure zone extending from Pakistan to the Bay of Bengal—leading to increased rainfall over the western coast.

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**Rain forecast: Cyclone Shakthi poses no threat to Maharashtra’s coast**

A senior IMD scientist in Mumbai told the *Indian Express*, “While the city is experiencing warm and sunny days at present, by October 6 and 7, it may get cloudy and start experiencing enhanced rainfall.” This change is due to the western disturbance impacting the region over the coming days.

Meanwhile, Cyclone Shakthi in the Arabian Sea is not expected to affect Maharashtra’s coast, as it is projected to move northwest after October 5.

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**Climatic shift: Why is the monsoon retreat delayed?**

The IMD officially declares the withdrawal of the monsoon after specific conditions are met, such as five consecutive days of dry weather, a shift in wind direction, reduced moisture levels, and noticeable changes in weather patterns.

While this year’s delay might seem unusual, Mumbai has experienced delayed monsoon withdrawals for six consecutive years. For example, in 2024, the monsoon withdrew on October 15, and in both 2023 and 2022, withdrawal occurred as late as October 23.

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**Rainfall data: Mumbai has received more than 3,100mm of rain this season**

Since the monsoon began in June, Mumbai has recorded significantly higher rainfall compared to its seasonal average. The Santacruz observatory reported over 3,100mm of rainfall so far, surpassing the average of 2,319mm.

Breaking it down monthly:
– June: 512mm
– July: 798mm
– August: 1,184mm
– September: 606mm

This substantial rainfall has contributed to the prolonged monsoon conditions and the wet start to October in Mumbai.
https://www.newsbytesapp.com/news/india/explained-why-mumbai-is-seeing-a-rainy-start-to-october/story

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