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 onwards. Salient Features of the 2025 Southwest Monsoon Season Rainfall over the country as a whole during the 2025 southwest monsoon season (June- September) was 108% of its long period average (LPA). Thus, the seasonal rainfall was above normal (>104% of LPA) as per the IMD forecast. All India Summer monsoon rainfall was 937.2 mm which is 5 th highest since 2001 and 38 th highest since 1901. Seasonal rainfall over Northwest India, Central India, South Peninsula, and Northeast India were 127%, 115%, 110% and 80% of the respective LPA. Rainfall over Northwest India was 747.9 mm which is highest since 2001 and 6 th highest since 1901, However, Rainfall over East & Northeast India was 1089.9 mm which is 2 nd lowest since 1901. The southwest monsoon seasonal (June to September) rainfall over the monsoon core zone, which consists of most of the rain-fed agriculture regions in the country, received 122% of LPA. Out of the 36 meteorological subdivisions, 2 subdivisions, covering 10% of the country’s total area, experienced large excess rainfall. Twelve subdivisions, constituting 35% of the area, received excess rainfall, while 19 subdivisions, representing 46%, recorded normal rainfall. The remaining 3 subdivisions, Arunachal Pradesh, Assam & Meghalaya, and Bihar accounting for 9% of the total area, experienced deficient rainfall during the season. Monthly rainfall over the country as a whole was 109% of LPA in June,105% in both July and August and 115% of LPA in September. The southwest monsoon advanced over the South Andaman Sea and Nicobar Islands on 13 May 2025, nearly nine days ahead of the normal schedule. It arrived in Kerala on 24 May 2025, ahead of the usual onset date of 1 June, and covered the entire country by 29 June 2025, earlier than the normal date of 8 July. The monsoon withdrawal began from west Rajasthan on 14 September, advancing by 3 days. There were Seven Monsoon Depressions formed during the season, out of that one intensified in to Deep Depression Category. There were 69 Low Pressure System Days against its normal 55 days. The seasonal forecast issued by IMD for the SW monsoon season rainfall was accurate, including the monsoon onset forecast over Kerala and ENSO and IOD forecast. Forecasts and progress of Southwest monsoon 2025 Long range forecast for the Southwest Monsoon Seasonal Rainfall during 2025 - First stage The southwest monsoon seasonal (June to September) rainfall over the country as a whole during 2025 is most likely to be above normal(>104% of the Long Period Average (LPA)). Quantitatively, the seasonal rainfall over the country as a whole is likely to be 105% of LPA with a model error of ± 5%. The LPA of the season rainfall over the country as a whole for the period 1971-2020 is 87 cm. To access the full forecast, click here. Onset Date of Southwest Monsoon - 2025 over Kerala This year, the forecast for the onset of southwest monsoon to set over Kerala was likely to be on 27th May with a model error of ± 4 days. The Southwest Monsoon has set in over Kerala on 24th May, 2025, against the normal date of 1st June. 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. Withdrawal of SW Monsoon Southwest monsoon has withdrawn from the entire country on 16th October, 2025. 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. Source : IMD