Incessant downpour over the weekend allowed Mumbai to record its second-highest 24-hour rain in the month of July in over the past five years.
The weather bureau had issued a yellow alert for Sunday but only light to moderate rain alert had been issued for Monday.
“Models have indicated heavy rain to continue on Sunday but the intensity of rain is likely to be lesser than Friday and Saturday,” KS Hosalikar, deputy director general of IMD’s western region, said.
On Sunday, the suburbs woke up to intense heavy rain with 95.4mm over a span of three hours from 8.30am to 11.30am, while south Mumbai recorded intermittent light showers of 9.4mm.
The Santacruz weather observatory, representative of the suburbs and Mumbai, recorded 200.8 mm rain between 8.30am on Saturday and 8.30am on Sunday, falling under the ‘very heavy’ rain category.
Last year, the city had recorded 375.2mm on July 2, which is the highest 24-hour rain in the month between 2015 and 2020. In 2018, it was 184.3mm (July 10), 163.4mm in 2017 (July 18), 114.5mm in 2016 (July 30), and 61 mm in 2015 (July 21).
Over the past decade, however, more rain was recorded in 2013 (215.6mm on July 24) and 2014 (207.2 mm on July 3). The all-time high 24-hour July rain was recorded during the July 27, 2005, deluge that led to 944.2mm.
The Colaba weather station, representative of south Mumbai, recorded 129.6 mm rain between 8.30am on Saturday and 8.30am on Sunday.
Over the past 48 hours—8.30am on Friday to 8.30am on Sunday—Mumbai suburbs recorded 357.8mm rain while south Mumbai recorded 298.6mm rain.
Thane recorded the highest rain across the Konkan region and the state over the past 24-hours at 377mm rain, which falls under the exceptionally heavy rain category.
The India Meteorological Department (IMD) further classifies 15.6-64.4mm as moderate rain while 64.5-115.5mm rain as heavy, 115.6-204.4mm as very heavy, and over 204.5mm as extremely heavy rain.
“North Konkan including Mumbai witnessed an active phase of the southwest monsoon over the past three days with continuous showers and extremely heavy rain in some areas. The impact of widespread rain activity led to overall excess rainfall for the majority of the weather stations,” Hosalikar said.
Mumbai suburbs has currently recorded 15% excess rain for the season while south Mumbai has recorded large excess of 29%.
Mumbai has so far recorded 480.4 mm rain (from July 1 to July 5, 11.30 am), which is 57% of the month’s average rainfall (840.7mm). The city had recorded 395 mm rain in June, which was the lowest monthly rain in five years.
However, with continuous downpour over 48 hours, the city has so far (from June 1 to July 5 11.30am) received almost 38% of its seasonal average rain (875 mm of 2,317 mm).
Independent meteorologists said weather systems responsible for heavy rain over Mumbai were expected to move northwards towards south Gujarat on Sunday leading to the decline in rain intensity for the city.
“Massive cloud bands in the Arabian Sea, as a result of the offshore trough, along with strong westerly winds led to these rains. While overnight intermittent heavy rain is expected and there may be some spillover for Sunday, major rain intensity will be felt for the Gujarat coast from Sunday,” Sridhar Balasubramanian, a professor with the department of mechanical engineering and IDP Climate Studies, Indian Institute of Technology, Bombay, said.
The city and suburbs can expect intermittent moderate rain through the day on Sunday with the possibility of heavy showers in isolated areas and light to moderate rain on Monday, IMD’s updated forecast on Sunday read.
Rain records during July over the past five years:
2020 (July 5) – 200.8mm
2019 (July 2) – 375.2mm
2018 (July 10) – 184.3mm
2017 (July 18) – 163.4mm
2016 (July 30) – 114.5mm
2015 (July 21) – 61mm
2013 (July 24) – 215.6mm (second highest July rain in 10 years)
2005 (July 27) – 944.2mm (all-time highest 24-hour rain)
Location-wise rainfall for 24-hours
Thane – 377mm
Haji Ali: 142mm
Malabar Hill: 129mm
Nariman Point: 105mm
(Source: India Meteorological Department)