Why Mumbai is sweltering this January: Three reasons

With residents reeling under hot and humid summer-like weather in the peak winter month of January, The Indian Express speaks to meteorologists and weather experts to understand why Mumbai is registering record-breaking maximum temperatures.

1. Moist south easterly winds; absence of Western Disturbances

Sushma Nair, scientist from IMD Mumbai, told The Indian Express, “The city is receiving an influx of south easterly winds, which are moist in nature, resulting in an increase in temperatures since the past one week. It is owing to these moist winds that not only have the temperatures increased, but people are experiencing discomfort too.”

According to Nair, typically, winters are associated with dry, northerly winds. “Mumbai experiences a drop in temperature when the northerly winds, that are dry, come in. However, this January, owing to the presence of moist South easterlies, the temperature has been higher.”

Attributing the presence of south easterlies to an anti cyclonic circulation, Mahesh Palawat from Skymet Weather Services said, “Once the south easterlies start clearing and become less prominent, it will allow the cool northerly winds to gush into the city. Once northerlies arrive, the temperature will start falling.”

Besides this, absence of western disturbances (WD) — which refers to heavy snowfall in the northern states — is another factor preventing a significant drop in the temperatures.

2. El Niño effect

Apart from this, some meteorologists have attributed the warmth of the ongoing winter to the fact that the country is currently experiencing an El Nino effect. El Nino refers to an abnormal warming of surface waters in the equatorial Pacific Ocean. Typically, the El Nino effect occurs every two to seven years, and leaves warmer weather in its wake. For perspective, 2016 — which was the hottest year on record before 2023 — was also an El Nino year.

Speaking to The Indian Express, a weather expert, requesting anonymity, said, “Whenever there is an El Niño, winters are warm whereas summers tend to be severe. While the El Nino year commenced in 2023, the next cycle of the event is usually even warmer. This could be another factor influencing the higher temperatures this season.”

3. Warming north Arabian Sea ushering in warm winds

For experts like Raghu Murtugudde, professor of climate studies at IIT Mumbai, the warming north Arabian Sea is amongst one of the prominent factors behind the warmer temperatures in Mumbai as well as the northwest Indian region.

Owing to global warming, the dry regions over the Middle East and Mediterranean are unable to lose their surface heat to space. According to Murtugudde, the heating in the Middle East and the associated low sea-level pressure pull the southwesterly winds over the Arabian Sea, resulting in the rapid warming of the Northern Arabian Sea.
Murtugudde explained, “With the Arabian Sea warming, warmer winds blow in from the sea into the region. Besides affecting the temperatures, it is also creating changes in monsoon patterns.”

So can Mumbaikars expect a drop in temperatures anytime soon?

Scientists have indicated that the maximum temperature is likely to oscillate between 32-33 degree Celsius for the next couple of days at least, before recording a slight dip.

Sushma Nair from IMD said, “For the next 2-3 days, the temperature may range between 31-32 degrees. But the situation may improve after that. While there won’t be a significant drop, the degree of discomfort that people are currently experiencing won’t be there.”

A bulletin by the weather bureau said, “Gradual fall in maximum temperatures over Konkan-Goa, Madhya Maharashtra and Marathwada region during 4-5 days. No large change in Maximum and Minimum temperatures over Vidarbha for next five days.”