Mumbai woke up to heavy overnight rains today, while all major subways in the city stayed open and traffic movement was largely smooth, officials said. The India Meteorological Department (IMD) issued a red alert for Mumbai and Palghar at 4 am, warning of thunderstorms, lightning, intense to very intense rainfall, and winds of 40-60 kmph. The alert was downgraded to an orange alert at 7 am for the next three hours, with moderate to intense spells of rain forecast for Mumbai, Thane, Raigad, Palghar and Sindhudurg districts. The southwest monsoon finally hit Mumbai on Tuesday, 13 days after its normal onset date, bringing much- needed relief from the sweltering heat.