May mayhem

The 2025 monsoon arrived a week early and raced across India in May, breaking records with its speed and intensity

- AKSHIT SANGOMLA AND PULAHA ROY

THIS MAY, India has seen an unprecedentedly early and rapid monsoon. The India Meteorological Department (IMD) officially reported Kerala's monsoon onset on May 24—a full week earlier than the usual June 1. Mizoram experienced rainfall on the same day, roughly 12 days earlier than normal. By May 26, the monsoon had reached Mumbai (its earliest arrival in 25 years) and was sweeping across Maharashtra, Karnataka, Telangana and even parts of Northeast India. Normally it takes 10-11 days for the monsoon to progress from Kerala to Mumbai, but this year that journey took barely two days.

Even before the calendar monsoon began, India saw torrential, unseasonal rain in May. An unusually high incidence of Western Disturbances, which are Mediterranean-origin storm systems, penetrated deep into India throughout May. IMD data record five to seven Western Disturbances in May 2025, well above the norm of one or two. The systems unleashed thunderstorms and heavy rains, breaking the usual pattern of searing heat. In the first week of May, half of India's 728 districts were already reporting large excess rainfall (more than 60 per cent of the normal rainfall for the week). By the last week of the month, the share of districts with large excess rainfall increased to 61 per cent. While the monsoon reached the subcontinent eight days ahead of schedule, half of the 728 districts in India were already reporting large excess rainfall in the first week of May. The trend persisted in the last week of the month.