Why is Mumbai experiencing a record-breaking heatwave in October. Mumbai’s record-breaking October heat is being driven by an anticyclonic system over southwest MP and Gujarat, bringing warm, dry winds and delaying the cooling sea breeze, according to Mahesh Palawat of Skymet Weather Services. The monsoon withdrew on October 3, earlier than the usual October 10–11 period, exposing Mumbai to heat sooner. Niño may also be contributing to high temperatures.