MUMBAI: The India Meteorological Department (IMD) further upgraded its weather warning for Mumbai after an orange alert was issued on Monday morning. The IMD issued a red alert for Mumbai, Thane, and Raigad at 12:38pm today, warning of extremely heavy rainfall at isolated locations.The Southwest Monsoon made a historic early arrival over Mumbai on May 26, 2025 — the earliest onset ever recorded for the city. The previous record for earliest onset was May 29, recorded in the years 1956, 1962, and 1971, with IMD records dating back to 1950. The onset over Mumbai comes just two days after the monsoon was declared over Kerala (May 24), and a day after its advance into parts of Maharashtra, up to Devgad (May 25).South Mumbai bore the brunt of the first spell.IMD’s Colaba observatory recorded 135.4 mm of rainfall in the 24 hours ending 8:30 am Monday, categorised as “very heavy rain” (115.6 mm–204.4 mm). In contrast, the Santacruz observatory in the suburbs recorded 33.5 mm.Colaba also broke the all-time rainfall record for May, logging 295 mm so far—surpassing the previous record of 279.4 mm set in May 1918. Even during Cyclone Tauktae in May 2021, the station had recorded slightly less rain at 257.8 mm for the month of May. Meanwhile, Santacruz has received 197.8 mm of rain this month.According to BMC’s Automatic Weather Stations (AWS), between 9:00 am and 10:00 am on Monday, Nariman Point Fire Station recorded the highest rainfall at 104 mm. This was followed by A Ward Office (86 mm), Colaba Pumping Station (83 mm), Municipal Head Office (80 mm), Colaba Fire Station (77 mm), Grant Road Eye Hospital (67 mm), Memonwada Fire Station (65 mm), Malabar Hill (63 mm), and D Ward (61 mm).In the eastern suburbs, Mankhurd Fire Station and MPS School recorded 16 mm, Nutan Vidya Mandir 14 mm, and Collector Colony 13 mm. In the western suburbs, Supari Tank, Gazadarbandh Storm Water Pump Station, and Khar Danda received 29 mm; SWM Workshop, HE Ward Office, and Vile Parle Fire Station saw 22 mm.Waterlogging was reported from Breach Candy, Kemps Corner, Sion Circle, Dadar TT, Hindmata, JJ Marg Post Office, Kurne Chowk, Bindu Madhav Junction (Worli), and Five Gardens.There were nine incidents of tree or branch falls—four in the city and five in the western suburbs.At Kemps Corner, a section of road was disrupted which locals said looked like a cave in. D Ward officials said the mastic asphalt layer had popped up due to water pressure and immediate repair work was undertaken.