Mumbai woke up to overcast skies and moderate showers as the first pre-monsoon rain spell of the season swept the region on Sunday morning. On June 1, Mumbai and its neighbouring districts of Thane, Palghar, and Raigad are slated to experience more wet spells, with the India Meteorological Department (IMD) issuing a yellow alert owing to the possibility of thunderstorms and moderate rain across the Konkan region.After a hot and humid Saturday, when temperatures surpassed 35 degrees Celsius across weather stations, moderate showers swept several pockets of Mumbai’s suburbs, the island city, and its neighbouring districts early on Sunday. Anticipating rain activity, the IMD issued two nowcast warnings for Mumbai and nearby districts; the first warning sounded at 5.40 am, followed by a fresh nowcast alert at 7 am owing to the likelihood of thunderstorms, moderate rain and gusty winds.Records furnished by the Brihanmumbai Municipal Corporation (BMC) showed that between 6 am and 9 am on Sunday morning, the eastern suburbs received maximum rain at 5 mm, followed by 2 mm of rainfall in the western suburbs and 0.61 mm in the city division.The heaviest spells were observed over Chembur, which received 27 mm of rainfall, followed by 22 mm in Mankhurd and Bandra Kurla Complex, 17 mm in Santacruz, 12 mm at the Gazdhar Bandh storm water pumping station and 11 mm in Ghatkopar.Data showed that between Saturday and Sunday, the IMD’s Santacruz observatory received 8.8 mm of rainfall while the Colaba observatory remained dry with “nil” rainfall.According to the IMD, more rain is likely to lash the city and other districts of the Konkan region, starting Monday. As per its weekly forecast bulletin, Mumbai is likely to witness light to moderate rain on Monday, followed by more rain activity on Tuesday when the IMD has issued a yellow alert owing to the possibility of thunderstorms and gusty winds alongside moderate rainfall. Meanwhile, Thane, Raigad, and Palghar districts have been placed under a yellow alert, starting Monday.The pre-monsoon spell is also likely to spur a drop in temperatures, with the IMD models forecasting maximum temperatures to oscillate between 32 and 33 degrees Celsius after June 1.Story continues below this adMeteorologists have attributed the incoming spells of rainfall to pre-monsoon activity, which is a typical feature in the region before the southwest monsoon sets in. The official date of the southwest monsoon onset is June 11 in Mumbai.