Mumbai has received its first post-monsoon heatwave warning after the India Meteorological Department issued a yellow alert for isolated pockets of Mumbai and Raigad for Friday, following a maximum temperature of 37.6°C at its Santacruz observatory on Thursday.
The reading was 4.5°C above normal and the highest recorded in Mumbai this year so far. Santacruz had recorded 35.4°C a day earlier. Colaba recorded a maximum of 36.5°C on Thursday, which was 3.9°C above normal, while the Thane-Belapur belt reached 37.2°C.
The warning came six days after the IMD announced the withdrawal of the southwest monsoon from Mumbai on October 3. On Thursday, the weather agency also declared the withdrawal of the monsoon from Maharashtra.
The IMD’s heatwave criteria for Mumbai and other coastal areas consider both the absolute temperature and the departure from normal. A heatwave is declared when the maximum temperature reaches at least 37°C and is 4.5°C or more above normal for two consecutive days.
The city’s minimum temperatures have not risen to the same extent. Santacruz recorded a minimum of 24.7°C, close to normal, while Colaba recorded 26.5°C, or 1.1°C above normal. Relative humidity remained high at 78% in Santacruz and 89% in Colaba.
Weather experts expect the hot spell to continue until October 14 or possibly into the middle of next week, with temperatures in Mumbai and parts of the Mumbai Metropolitan Region potentially approaching 39°C. Independent weather observer Abhijit Modak attributed the rise to a persistent high-pressure area over Gujarat and easterly to northeasterly winds that are suppressing the sea breeze over the Konkan region.
Modak also linked the conditions to the early withdrawal of the monsoon, below-normal rainfall in September and the absence of a significant post-monsoon thunderstorm spell. These factors have reduced moisture and cloud cover, allowing land surfaces to heat more rapidly during the day.
Doctors have warned residents, particularly those working or travelling outdoors, to watch for symptoms of heat exhaustion. Dr Nitin Karnik, head of the department of medicine at Sion Hospital, said heavy sweating, dizziness, headache, fatigue and fainting were commonly observed during periods of high temperature.
Dr Gautam Bhansali, senior consultant physician at Bombay Hospital, said Mumbai’s limited air circulation and high humidity can contribute to severe dehydration and affect the kidneys. He said the hospital was treating two patients admitted with severely low blood pressure, and advised residents to remain hydrated and cover their heads while outdoors.
The highest October maximum recorded at Santacruz is 38.6°C, recorded on October 17, 2015. Colaba’s October record is 39.5°C, recorded on October 22, 1968. The IMD’s alert and the forecast of temperatures nearing 39°C will remain the immediate reference points for residents and authorities as the hot spell continues.
