Surat has a tropical savanna climate, moderated strongly by the Arabian Sea. The summer begins in early March and lasts till June. April and May are the hottest months, the average maximum temperature being 40 °C (104 °F). Monsoon begins in late June and the city receives about 1,000 millimetres (39 in) of rain by the end of September, with the average maximum being 32 °C (90 °F) during those months. October and November see the retreat of the monsoon and a return of high temperatures till late November. Winter starts in December and ends in late February, with average temperatures of around 23 °C (73 °F), and little rain.
Very often heavy monsoon rain brings floods in the Tapi basin area. In last two decades, the city has witnessed major floods every four years, the worst being the flood of August 2006, perhaps the costliest in the city's history. In the second week of August 2006, a massive flood caused severe damage to the city of Surat. According to a report released by Indian Institute of Management – Ahmedabad (IIM-A), massive flood after release of water from Ukai Dam had caused major human tragedy and property damage estimated at Rs 220 billion on that day. In less than three days, at least 150 people died directly due to flood and many other due to water-borne diseases that followed. More than 1500 animal carcasses were later hauled out of the mud
