Red alert for heavy rains in Mumbai — why the maximum city is not equipped to handle it

The IMD (India Meteorological Department) on Saturday issued a red alert for Mumbai, Thane, Raigad and Palghar districts, warning of extremely heavy rainfall on Sunday with the likelihood of very intense spells in isolated areas.

The alert raises concerns not just about temporary disruption, but about the city's broader vulnerability to climate-driven weather extremes.

“Extremely heavy rainfall is likely over Mumbai, Thane, Raigad and Palghar districts with very intense spells in some areas. Coastal districts such as Ratnagiri and Sindhudurg, along with the ghat regions of Nashik, are also expected to witness heavy showers,” said an IMD official, updating the forecast on Saturday afternoon.

The red alert comes after an earlier orange warning, issued Saturday morning, was upgraded based on updated weather models predicting heightened monsoon activity along the Konkan belt.

While parts of north Maharashtra, central Maharashtra, Marathwada and Vidarbha are likely to see only light to moderate showers, the Mumbai metropolitan region could experience rainfall exceeding 204.5 mm in a 24-hour period — the threshold for red alert conditions.

On Saturday, overcast skies dominated Mumbai, with intermittent light to moderate showers reported across several areas. According to civic officials, the island city recorded 30.07 mm of rain in the 24 hours ending at 8 am. The eastern suburbs saw 26.12 mm, while the western suburbs recorded 9.99 mm. While traffic remained largely unaffected, local train services were delayed on some lines.

A city at risk

Though Mumbai is no stranger to heavy rainfall during the monsoon, its growing urban footprint, outdated drainage systems, and widespread concretisation have made it increasingly vulnerable to flooding. Low-lying neighbourhoods such as Kurla, Dadar, and Sion often see waterlogging within an hour of intense rain, sometimes disrupting road and rail transport for hours — or even days.

The situation is made worse by blocked stormwater drains, illegal construction on natural waterways, and the near-disappearance of the city’s once-thriving wetlands and mangroves.

In recent years, such extreme rainfall events have become more frequent and intense. According to data from the IMD and climate researchers, Mumbai now sees more days each monsoon where rainfall exceeds 100 mm or even 200 mm in 24 hours — a significant rise from past decades.

Climate warning signs

The IPCC (Intergovernmental Panel on Climate Change), in its Sixth Assessment Report, flagged Mumbai as one of the global cities at high risk from sea-level rise, coastal flooding, and extreme precipitation events. Urban centres like Mumbai, it warned, are particularly susceptible because of population density, poor infrastructure planning, and climate-incompatible growth.

“Urbanisation combined with more frequent heavy rainfall increases the likelihood of flooding, especially when cities are built over wetlands and natural drainage channels,” the report noted. The IPCC also emphasised that cities in South Asia urgently need to upgrade infrastructure and adopt climate-resilient planning.

While red alerts are not uncommon during the monsoon, the rising number of high-intensity rainfall events in shorter windows is a worrying trend. The IMD has also acknowledged this pattern, stating that monsoon rains are becoming more erratic — marked by long dry spells followed by sudden cloudbursts.

Civic readiness and appeal to citizens

Authorities in Mumbai and surrounding districts have been placed on high alert, and disaster response teams are on standby. The BMC has advised residents to avoid non-essential travel, especially in flood-prone zones, and to follow official advisories closely.

As climate volatility becomes the new normal, experts say the city will need more than weather alerts — it requires investment in sustainable drainage, green cover, and resilient public infrastructure to keep pace with changing monsoon dynamics.