Mumbai has received its first post-monsoon heatwave warning after the India Meteorological Department issued a yellow alert for isolated pockets of the city and Raigad on October 9, with daytime temperatures rising sharply above normal soon after the southwest monsoon withdrew.
The warning was issued on Thursday, six days after the IMD announced the withdrawal of the southwest monsoon from Mumbai on October 3. The department also declared the withdrawal of the southwest monsoon from the whole of Maharashtra on Thursday, marking a rapid shift from monsoon conditions to unusually hot weather.
Mumbai’s Santacruz observatory recorded a maximum temperature of 37.6°C on Thursday, which was 4.5°C above normal. Colaba recorded 36.5°C, or 3.9°C above normal, while the Thane-Belapur belt recorded 37.2°C. The rise followed a sharp increase from the previous day, when the maximum temperatures at Colaba and Santacruz were 34°C and 35.4°C respectively.
For Mumbai and other coastal areas, the IMD’s heatwave criteria consider both the absolute temperature and its departure from normal. A heatwave is declared when the maximum temperature reaches at least 37°C and remains 4.5°C or more above normal for two consecutive days. Santacruz’s Thursday reading was also its highest October temperature in eight years. The observatory’s highest October maximum last year was 37°C, recorded on October 17.
The recent October maximum temperatures at Santacruz were 36.5°C in 2025, 37.4°C in 2024, 37.4°C in 2023, 35.4°C in 2022, 36.4°C in 2021, 35°C in 2020 and 36.6°C in 2019. At Colaba, Thursday’s 36.5°C was the highest October maximum since 2019, when the observatory recorded 37.2°C. The city’s all-time October records remain higher: 39.5°C at Colaba on October 22, 1968, and 38.6°C at Santacruz on October 17, 2015.
The heat has been concentrated in the afternoons. Santacruz recorded a minimum temperature of 24.7°C on Thursday, close to normal, while Colaba recorded 26.5°C, 1.1°C above normal. However, relative humidity remained high at 78% at Santacruz and 89% at Colaba, adding to the discomfort for residents and people working outdoors.
Independent weather observer Abhijit Modak attributed the sharp rise to a persistent high-pressure area over Gujarat and easterly to northeasterly winds that are suppressing Mumbai’s sea breeze. He said the conditions could push temperatures in Mumbai and parts of the Mumbai Metropolitan Region towards 39°C in the coming days. Modak also linked the heat to the early monsoon withdrawal, below-normal rainfall in September and the absence of a significant post-monsoon thunderstorm spell, which have reduced moisture and cloud cover.
The hot spell is expected to continue through October 14 or possibly into the middle of next week, with temperatures potentially peaking around October 14, according to the weather assessment cited by The Times of India. The IMD’s yellow alert remains in force for isolated pockets of Mumbai and Raigad on October 9.
