Mumbai rainfall ended September below normal, with the city’s Santacruz observatory recording 306.6 mm during the final month of the monsoon—about 15% below its monthly average of 359.6 mm. The reading was the second lowest September total recorded there in the past decade.
The shortfall was sharper in south Mumbai. The Colaba weather station recorded 175.1 mm in September, less than half its monthly average of 359.6 mm. It was the second-lowest September rainfall at Colaba in 20 years and the third-lowest in 25 years, according to data reported by the Times of India.
September is normally the last month of Mumbai’s southwest monsoon season. The lowest September rainfall recorded in the reported comparison was in 2018, when Santacruz received 73.1 mm and Colaba recorded 59.5 mm.
The September deficit has not, however, made the overall monsoon season uniformly poor across the city. Santacruz has recorded 2,530.5 mm over the four-month season, exceeding its seasonal average of 2,318.8 mm. Colaba’s seasonal total stands at 1,957.1 mm, below its average of 2,094.6 mm.
The contrasting station readings show how unevenly rainfall has been distributed across Mumbai. Santacruz serves as the benchmark observatory for the city, while Colaba’s figures indicate a substantially drier season in south Mumbai. For residents and city agencies, the distribution of rainfall is significant because cumulative seasonal totals do not show when or where rain arrived.
Independent weather forecaster Rajesh Kapadia described the season as sporadic rather than evenly distributed. He said rainfall was vigorous when weather systems arrived, but that there was a prolonged lull after August 15 because systems from the Bay of Bengal were not moving westwards towards Madhya Pradesh and Maharashtra.
Kapadia attributed the changing movement of these systems partly to a strengthening El Niño after August and the influence of an anticyclone over western India. These factors, he said, affected the tracks of the weather systems that bring rain towards Mumbai and surrounding regions.
Kapadia expects the monsoon to begin withdrawing from the city from Saturday. October 8 is the normal withdrawal date for Mumbai, according to the report. The next stage of the season will determine whether the city’s late-monsoon rainfall remains below normal at both observatories.