The India Meteorological Department (IMD) has officially declared the onset of the southwest monsoon over Kerala on Thursday, June 4, 2026, signaling the beginning of the country's four-month rainy season from June to September.
Monsoon Progress and Coverage
According to the IMD, the southwest monsoon has advanced into several regions, including the remaining parts of the southwest and southeast Arabian Sea, parts of the west central and east central Arabian Sea, the entire Lakshadweep islands, Kerala, and some areas of Karnataka and Tamil Nadu. It has also covered the remaining parts of the Comorin area, the southeast Bay of Bengal, and additional portions of the southwest, west central, east central, and northeast Bay of Bengal as of June 4, 2026.
Delayed Onset Compared to Forecast
The onset of the monsoon this year is later than the IMD's earlier forecast of May 26. Typically, the southwest monsoon arrives in Kerala around June 1, making this year's arrival slightly delayed but within the normal range.
Revised Rainfall Outlook
The development comes days after the weather department revised its seasonal rainfall outlook, indicating that rainfall across the country is expected to be below normal this year. The IMD has forecasted that India will receive rainfall amounting to approximately 90% of the long-period average (LPA). The LPA is calculated based on rainfall data from 1971 to 2020, with the country's seasonal LPA standing at 87 cm. If the monsoon season records less than 90% of the LPA, the IMD classifies it as 'deficient'.
Potential El Nino Impact
Meteorologists have pointed to the possible development of El Nino conditions as a contributing factor to lower rainfall during the monsoon season. Currently, neutral El Nino-Southern Oscillation (ENSO) conditions are gradually shifting toward El Nino conditions over the equatorial Pacific Ocean. The IMD has stated that El Nino conditions are likely to remain weak during June but could strengthen to moderate or strong levels by September.
This forecast underscores the importance of monitoring weather patterns closely, as below-normal rainfall could impact agriculture, water resources, and the overall economy. The IMD continues to provide updates and advisories to help stakeholders prepare for the season.
