MUMBAI: After experiencing its fourth-wettest July in nearly a decade, Mumbai saw an unusually subdued month, recording its third-lowest Aug rainfall in 10 years.The IMD’s Santacruz observatory (the city’s benchmark) recorded 315.3mm of rainfall between Aug 1 and 30. Only two Augusts in the past 10 years recorded lower rainfall: 177.2mm in 2023 and 235.2mm in 2018.The pattern was similar in south Mumbai. The Colaba observatory recorded 164.4mm, making it the third-lowest Aug rainfall recorded there in 10 years. Colaba had received just 111.5mm in Aug 2023 and 188.7mm in Aug 2018.The shortfall is significant when compared with the normal Aug rainfall. Santacruz and Colaba typically receive 566.4mm and 482.1mm, respectively, during the month.Unlike the preceding months, when Mumbai experienced several intense spells of rain, Aug passed without a major heavy-rain episode, resulting in a relatively dry month across the city.Weather enthusiast Athreya Shetty attributed the subdued Aug rainfall to the absence of an offshore trough and strong weather systems from the Bay of Bengal.The contrast with July was particularly stark. The Colaba observatory recorded 1,176.5mm of rainfall in July this year, while Santacruz received 1,491.9mm.
Monsoon stats
The below-normal Aug rainfall has caused little immediate concern on the water-supply front. The lakes supplying Mumbai are currently holding around 96% of their total useful water stock, leaving the city in a comfortable position as the monsoon enters its final stretch. The BMC has continued with the existing 10% water cut.The overall monsoon rainfall remains healthy. The normal seasonal rainfall for Colaba and Santacruz is 2,094.6mm and 2,318.8mm, respectively. Santacruz is close to its seasonal average, having recorded 2,223.6mm so far this monsoon, while Colaba remains below its benchmark, with 1,782mm recorded to date.Weather enthusiast Athreya Shetty said, “Frequent incursions of dry air from Central Asia, coupled with strong El Nino conditions and MJO suppression, prevented Bay of Bengal systems from moving closer to the west coast and kept the Arabian Sea largely dormant through the month.”Another weather enthusiast, Abhijit Modak, said the sharp contrast between July and August was largely driven by changing synoptic conditions over the region.“During July, several monsoon systems were able to propagate westward, repeatedly strengthening the monsoon flow over Maharashtra. This favoured strong moisture transport towards the west coast, enhanced the offshore trough, and produced several intense rainfall spells over Mumbai and the wider MMR,” Modak said.“Aug presented a very different scenario. Successive Bay of Bengal systems struggled to make significant westward progress because of persistent dry-air intrusion from the northwest and the adjoining Middle East region. This acted as a major barrier to the westward propagation of the systems.”
