Southwest monsoon - an overview The period June to September is referred to as the 'Southwest Monsoon' period. Southwest Monsoon period is the principal rainy season for the Indian subcontinent. The whole country receives nearly 75% of its rainfall during this period. The advance of the southwest monsoon over the Indian mainland is marked by monsoon onset over Kerala and is an important indicator characterizing the transition from the hot and dry season to the rainy season. As the monsoon progresses northward, relief from scorching summer temperatures is experienced over the areas. Southwest monsoon normally sets in over Kerala on 1st June with a standard deviation of about 7 days. India Meteorological Department (IMD) has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 on/wards. South West Monsoon 2026 Salient Features of the 2026 Southwest Monsoon Season Rainfall over the country as a whole during the 2026 southwest monsoon season (June- September) was 87% of its long period average (LPA). All India Summer monsoon rainfall was 759.4 mm which is 4th lowest since 2001 and 13th lowest since 1901. Seasonal rainfall over Northwest India, Central India, South Peninsula, and Northeast India were 94.1%, 97%, 76% and 74% of the respective LPA. Rainfall over East & Northeast India was 1017.1 mm which is lowest since 1901 and South Peninsula was 542.0 mm which is 4th lowest since 1901 and 2nd lowest since 2001. However, Central India receive normal rainfall The southwest monsoon season (June to September) rainfall over the monsoon core zone, which consists of most of the rain-fed agriculture regions in the country, received 779.9mm rainfall which is less the lower limit of normal category (782.8 to 881.2). Out of the 36 meteorological subdivisions, eighteen subdivisions, constituting 53% of the area, received normal rainfall, while 17 subdivisions, representing 42%, recorded deficient rainfall. The remaining one subdivision (Odisha), covering 5% of the country's total area, experienced excess rainfall during the season. Monthly rainfall over the country as a whole was 65% of LPA in June, 101% LPA in July, 84%LPA August and 92% of LPA in September. The southwest monsoon advanced over the South Andaman Sea and Nicobar Islands on 16 May 2026, nearly six days earlier than the normal schedule. It arrived in Kerala on 4th June 2026, 3 days later than the climatological normal onset date of 1 June, and covered the entire country by 9th July 2026, near normal date of 8 July. The monsoon withdrawal began from west Rajasthan on 19 September, delayed by 2 days. There were 14 low pressure systems, including six Monsoon Depressions during the season, out of that three intensified in to Deep Depression. There were 77 Low Pressure System Days against its normal 57 days. The seasonal forecast issued by IMD for the SW monsoon season rainfall was accurate and within the forecast error limit, while the forecasts of ENSO and IOD conditions were broadly consistent with their observed evolution. However, the forecast of monsoon onset over Kerala was 8-day early as compared to actual date of onset. To read the complete report, click here. Outlook for the Rainfall during Second Half of the SW Monsoon Season (August – September 2026) The rainfall averaged over the entire country from August to September 2026 is likely to be below normal (<94% of the Long Period Average (LPA)). The LPA of rainfall over the country as a whole during the August to September period, based on historical data of 1971 to 2020 is 422.8 mm. During this period, below-normal rainfall is very likely over many parts of the country except some parts of the Peninsular India, Central India, northern parts of northwest India and East & Northeast India where normal to abovenormal rainfall is likely. Withdrawal of SW Monsoon The withdrawal of the Southwest Monsoon 2026 commenced on 19 September, 2 days delayed by its normal date of September 17. To view the withdrawal of Southwest Monsoon across the country, click here. Cyclone information To view the cyclone information, click here. Warnings Warnings are issued as a for a five day Subdivision and district levels. To view the warnings issued, click here. Progress of Southwest Monsoon To view the progress of Southwest Monsoon across the country, click here. Daily monsoon activity To view the daily monsoon activity of Southwest Monsoon across the country, click here. Onset Date of Southwest Monsoon - 2026 over Keralam This year, the forecast for the onset of southwest monsoon to set over Keralam was initially forecasted to be on 26th May with a model error of ± 4 days. It was later revised to be between May 28 and June 3. The southwest monsoon set in over Keralam on 4th June, 2026. Southwest monsoon advanced over parts of south Bay of Bengal, Andaman Sea and Andaman & Nicobar Islands on 16th May, 2026. Updated Long Range Forecast for the Southwest Monsoon Seasonal Rainfall during June-September 2026 - May 29, 2026 Quantitatively, the southwest monsoon seasonal rainfall over the country as a whole is likely to be 90% of the Long Period Average (LPA) with a model error of ±4%, indicating that below normal rainfall is most likely over the country as a whole during the monsoon season (June to September), 2026. The southwest monsoon seasonal (June to September, 2026) rainfall is most likely to be normal over Northeast India (94-106% of LPA) and below normal over Central & South Peninsular India (<94% of LPA) and Northwest India (<92% of LPA). The southwest monsoon seasonal rainfall over the Monsoon Core Zone (MCZ) consisting of most of the rainfed agriculture areas in the country is most likely to be below normal (<94% of LPA). During June to September 2026, below-normal seasonal rainfall is most likely over most parts of the country, except some areas over Northwest and northeast India, eastern parts of south peninsula and adjoining areas of east-central India and isolated pockets of East India, where normal to above normal rainfall is likely. The average rainfall for the country as a whole during June 2026 is most likely to be below normal (<92% of LPA). Updated Long Range Forecast For the 2026 Southwest Monsoon Season Rainfall - June - September 2026 First Long Range forecast for the 2026 Southwest Monsoon Season Rainfall - Highlights - April 13, 2026 The 2026 southwest monsoon seasonal (June to September) rainfall over the country as a whole is most likely to be below normal (95-90% of the Long Period Average (LPA)). Quantitatively, the seasonal rainfall over the country as a whole is likely to be 92% of LPA with a model error of (plus/minus 5)% . The LPA of the seasonal rainfall over the country as a whole based on the period of 1971-2020 is 87 cm. At present, Weak La Niña-like conditions are transitioning to ENSO-neutral conditions over the equatorial Pacific. Atmospheric circulation features across the tropical Pacific remain consistent with weak La Niña-like conditions. The Monsoon Mission Climate Forecast System (MMCFS) suggests the development of El Niño conditions during the SW Monsoon season. At present, neutral Indian Ocean Dipole (IOD) conditions are present over the Indian Ocean and the latest Climate models forecast indicates that the positive IOD conditions are likely to develop towards the end of the southwest monsoon season. The northern hemisphere snow cover extent during the last three months (January to March 2026) was slightly below normal. Winter and spring snow cover extent over Northern Hemisphere as well as Eurasia has a general inverse relationship with the subsequent southwest monsoon seasonal rainfall over the country. First Long Range Forecast For the 2026 Southwest Monsoon Season Rainfall Source : IMD