The monsoon is likely to reach Mumbai a week to 10 days late this year, according private weather forecaster Skymet Weather. While the southwest monsoon usually hits the city between June 8 and June 10 — a week after the first rains in Kerala — the onset this year could take place between June 15 and June 18, or even as late as June 20, said Skymet.

Last year, the monsoon hit Mumbai on June 9. The weak and delayed onset is bad news for a city already grappling with water shortage. The Mumbai civic body has imposed a 10% water cut across the city to preserve stock until the rains arrive.

“The seven lakes supplying water to Mumbai have a little less than 15% water stock till May 12. A good monsoon is crucial,” said an official from the Brihanmumbai Municipal Corporation (BMC).

Skymet has also predicted deficient rainfall in June and July across Maharashtra, many regions of which are facing the worst drought in years.

The delay in the onset could be attributed to a lingering El Niño, a weather phenomenon characterised by warm ocean temperatures in the equatorial Pacific Ocean that is associated with poor rainfall and more heat waves in the subcontinent.

“Our weather models show the strong weather systems that are expected to develop by the first week of June and pave the way for the monsoon, are absent. As a result, the rains could be delayed by at least a week,” said Mahesh Palawat, vice-president (meteorology and climate change), Skymet.

Palawat said the onset in Kerala, too, is likely to be delayed owing to a 60% chance of the El Niño influencing the monsoon between June and August.

“There is a slight positive Indian Ocean Dipole (IOD) indicator, a phenomenon in the Indian Ocean that cools sea surface temperature and offsets negative effects of El Niño. However, it won’t be able to overpower El Niño in June and July,” Palawat said. This means, heavy rain can be ruled out in Mumbai in the first half of the monsoon, Palawat said. “Overall, Mumbai and Maharashtra will see deficient rain in June and July, but this is expected to improve to normal levels in August and September,” Palawat said.

First Published: May 14, 2019 01:35 IST