Summer relief on cards: Why Mumbai and neighbouring districts are set to experience rain in April?

Why are Mumbai and nearby regions set to experience showers?

A trough which was running from interior Odisha to Kanniyakumari is currently running from south Chhattisgarh to north interior Tamil Nadu. This trough—which will lead to the northeasterly winds prevailing in the lower level over the region—is presently running across interior parts of Maharashtra and Karnataka at 0.9 km above mean sea.

Sushma Nair, a scientist from IMD Mumbai, said that the presence of the trough will result in the interaction of easterly and westerly winds—in what will lead to favourable conditions for rain activity in the region.

While the intensity of rain will be varied across the region with pockets like Mumbai likely to receive only light showers during the afternoon or evenings, its neighbouring areas like Thane, Palghar and Raigad are forecast to experience thunderstorms accompanied with lightning, moderate rainfall as well as gusty winds with speeds of up to 30-40 kmph in isolated pockets.

“The trough will be instrumental in bringing rain across the region. But the intensity of rains in Mumbai will be patchy and light. In contrast, the intensity will be much stronger over Pune and parts of interior Maharashtra,” said Mahesh Palaway of Skymet Weather Services.

Is rain unusual for Mumbai in March/April?

According to meteorologists, Mumbai is no stranger to unseasonal rainfall during the summer months. “Such pre-monsoon showers are very common during this season owing to the interaction of westerly and easterly winds,” said Sushma Nair of the IMD.

Take a case in point from the previous years with records reflecting brief spells of showers in March and April. Data furnished by the IMD shows that Mumbai’s Santacruz station recorded its heaviest showers for March in 2023 when it logged 17.1 mm rain on March 21, followed by 10 mm rain in 2016 and 13 mm rain in the year 2015. Meanwhile, records for April show that Mumbai recorded its wettest April day ever in 2023 when it received 14.8 mm rain.

Typically, Mumbai receives trace (too insignificant to be measured) pre-monsoon showers between April and May, leading up to the monsoon season. In Mumbai, the official date of monsoon onset oscillates between June 9-11.

How will rain affect temperatures in Mumbai?

The pre-monsoon showers are likely to spur a dip in temperatures in the coastal city amid forecasts of maximum temperatures stated to hover around 32 degrees Celsius after April 2. This will mark a significant drop from the current temperatures which touched highs of 36 degrees Celsius—nearly three degrees above normal—on Saturday.

However, this respite is likely to be short-lived. Weather experts maintained that the showers do not signify long-time changes in Mumbai’s temperatures, which may spike after the current system passes.

Palawat of Skymet Weather Services told The Indian Express, “For the first week of April, the trough system will usher in light rain and some relief from heat. However, depending on the pre-monsoon activity, which is typically less during this season, Mumbai may experience very hot weather in the second half of April and in May.”