Mumbai weather updates: City sizzles by day, shivers by night 2

City was covered in fog last month. File pic/Shadab Khan

Mumbai has been experiencing a temperature fluctuation of roughly 7 to 8 degrees Celsius between the maximum and minimum temperatures in recent days. However, on Friday, January 3, the city recorded nearly a 20-degree gap between daytime and nighttime temperatures, a range meteorologists consider highly unusual for this time of year.

Although temperature fluctuations are common during this period, Friday's 19.7°C swing is not typical for January, said meteorologists. "This is not common or normal in January," remarked climatologist Rajesh Kapadia from the private weather blog Vagaries of Weather. "This kind of difference has been witnessed in March. It happened because the night was still and cool, allowing temperatures to drop, while warm easterly winds during the day pushed the mercury up."

According to Kapadia, on March 16, 2011, the difference between the maximum and minimum temperatures reached 22.1 degrees Celsius. Sunil Kamble, director of IMD Mumbai, acknowledged the unusual swing but urged caution before calling it extraordinary. "Yes, there is a vast difference between daytime and nighttime temperatures on Friday. However, this phenomenon has been observed over the past few years. It would be premature to label it unusual based on a single day's data," Kamble said. He added that detailed studies and a closer look at temperature patterns over time are necessary to determine the true extent of this variation.

What is DTR?

The significant spike in both daytime and nighttime temperatures places renewed attention on the concept of diurnal temperature range (DTR), the difference between the day's highest and lowest temperatures. Although peninsular regions generally exhibit a lower DTR due to oceanic influence, parts of northwestern India often experience higher fluctuations because of lower rainfall and greater distance from the sea.

However, shifting wind patterns and other meteorological factors mean local variations can and do occur. Meteorologists point to anticyclonic phenomena and resultant wind direction changes as contributing factors to fluctuations like these. Another factor often cited is "global brightening." Observed since the late 1980s, this phenomenon, where reduced cloud cover allows more sunlight to reach the Earth's surface, causes a spike in daytime temperatures. Although its impact on Mumbai's recent warm spell remains to be studied in greater depth, experts note it could be one of several contributing factors.

Highest Jan temp since 2016

Friday's maximum of 36°C was the highest daytime temperature recorded in Mumbai in January since 2016. The IMD's extreme weather records show the city hit 37.3°C on January 1, 2016. Kamble confirmed that Friday's reading marks the first time in nine years that the city has touched 36°C in January.

Forecast

According to the Mumbai weather updates of the Indian Meteorological Department (IMD), Mumbai's Santacruz observatory (which covers suburban Mumbai) recorded a maximum temperature of 36 degrees Celsius and a minimum temperature of 16.7 degrees Celsius. The Colaba observatory, which covers South Mumbai, recorded a maximum temperature of 33.2 degrees Celsius and a minimum of 21.5 degrees Celsius.

The relative humidity was 84 per cent in Santacruz and 70 per cent in Colaba. Despite the high daytime readings, nights have brought a noticeable chill. The IMD forecasts a clear sky over the next 24 to 48 hours, with maximum temperatures likely to remain between 35°C and 36°C, while minimums may hover around 17°C to 18°C. "Some fluctuation between day and night temperatures is expected to continue," said an official from the IMD's Regional Meteorological Centre in Mumbai.