Mumbai reels under earliest ever arrival of monsoon, wettest May in 100 years

MUMBAI: The southwest monsoon hit Mumbai on Monday - the earliest onset ever recorded for the city. The previous record was May 29, recorded in 1956, 1962, and 1971 (records date back to 1950). The early onset coincided with the island city breaking a 100-year-old record for rainfall received in May, which has now touched 295mm.

Shubhangi Bhute, head of IMD Mumbai , said, "Typically, the monsoon sets in around June 11, so this year's onset is significantly early... Tomorrow, Mumbai will be under a yellow alert."

IMD's Colaba observatory, which broke the all-time rainfall record for May, logging 439 mm so far, surpassed the previous record of 279.4 mm set in May 1918. Even during Cyclone Tauktae in May 2021, the station had recorded slightly less rain at 257.8 mm. The Santacruz observatory, which covers the suburbs, has so far recorded 272 mm of rain this month. The record for the highest rainall in May at Santacruz stands at 387mm in the year 2000.

South Mumbai was hit hardest in the first wave of showers. According to IMD, average rainfall recorded between 8.30am and 5.30pm was 144.3 mm at Colaba - classified as "very heavy rain" (115.6-204.4 mm) - and 74.3 mm at Santacruz, falling under the "heavy rain" category (64.5-115.5 mm). However, more granular data from BMC's automatic weather stations revealed that Nariman Point alone received 104 mm of rain in just one hour on Monday morning.

IMD, however, did not call this a cloudburst; it said it was an 'intense rain spell'. A cloudburst is typically defined as extremely intense rainfall over a small area, usually 100 mm or more in one hour, which often leads to flash floods, landslides, and severe water logging.

The showers exposed the city's unpreparedness as areas which had never been flooded earlier also witnessed waterlogging, including the newly opened underground Acharya Atre Chowk Metro station. In fact, access to Mantralaya was partially waterlogged and govt employees had to wade through knee-deep water.

Suburban train services, especially Harbour line, were hit by waterlogging. Over 50 Central Railway services and 18 Western Railway services were cancelled.

Heavy rain and dense cloud cover also disrupted flight operations. An Air India flight from Ahmedabad to Mumbai was diverted back to Ahmedabad, while another from Goa was diverted to Indore, said sources.

Wall and building collapses and tree fall were reported from Mahim, Malabar Hill, and Teen Batti area. A road in Kemps Corner cracked open. A dozen BEST buses were stuck on waterlogged roads and 20 routes diverted.