India Meteorological Department Releases 2023 Southwest Monsoon End of Season Report

New Delhi, October 1, 2023 – The India Meteorological Department (IMD) has recently issued its Southwest Monsoon End of Season Report for 2023, shedding light on crucial details regarding this year’s monsoon season. Here are the key highlights from the report:

• Overall Rainfall: The monsoon season, spanning from June to September, witnessed rainfall across the country amounting to 94% of its long period average (LPA). This indicates that the monsoon was near-normal for the year.
• Regional Variations: Different regions of India experienced varying degrees of rainfall. Northwest India received 101% of its LPA, Central India received 100%, South Peninsula received 92%, and Northeast (NE) India received 82% of their respective LPAs.
• Monsoon Core Zone: The monsoon core zone, comprising most of the rainfed agricultural regions in the country, received 101% of its LPA, classifying it as a normal monsoon season.
• Subdivision Breakdown: Out of India’s 36 meteorological subdivisions, 3 subdivisions (9% of the country’s area) received excess rainfall, 26 subdivisions (73% of the area) received normal rainfall, and 7 subdivisions (18% of the area) experienced deficient season rainfall. Notable among those with deficient rainfall are Nagaland, Manipur, Mizoram & Tripura (NMMT), Gangetic West Bengal, Jharkhand, Bihar, East UP, South interior Karnataka, and Kerala.
• Monthly Rainfall: Monthly rainfall percentages varied throughout the monsoon season, with June receiving 91% of LPA, July with 113%, August at 64%, and September at 113% of LPA.
• Monsoon Onset: The monsoon onset began in the south Andaman Sea and Nicobar Islands on May 19th, slightly ahead of its normal date, but it was delayed in reaching Kerala, arriving on June 8th.
• Monsoon Withdrawal: Monsoon withdrawal started on September 25th in west Rajasthan, delayed by 8 days compared to the normal date.
• Accuracy of Monsoon Onset Forecast: The IMD’s forecast for the monsoon onset over Kerala in 2023 was correct, marking the seventeenth consecutive correct forecast for this event, except for the year 2015, since it started in 2005.
• Seasonal Rainfall Forecast Accuracy: The forecasts for seasonal rainfall across the country were quite accurate, with actual rainfall at 94% of LPA, just slightly below the forecasted 96% ± 4%.
• Influence of Climate Drivers: The report also discusses the influence of climate drivers such as El Niño, La Niña, and the Indian Ocean Dipole (IOD) on the monsoon. El Niño events are often linked to below-average rainfall in India, while La Niña events correlate with above-average precipitation. Positive IOD conditions tend to bring above-average rainfall, while negative IOD corresponds to below-average rainfall in certain regions.
• Intra-seasonal Variation: The report highlights intra-seasonal variations, showing the impact of the Madden Julian Oscillation (MJO) on the monsoon’s progress during 2023.
• Verification of Long-Range Forecasts: The IMD’s long-range forecasts for monsoon onset and seasonal rainfall were verified. The onset forecast for Kerala was correct, while the seasonal rainfall forecast was reasonably accurate.

In summary, the 2023 southwest monsoon season in India witnessed near-normal rainfall, with regional variations in precipitation levels. The IMD’s forecasts for monsoon onset and seasonal rainfall were generally reliable, contributing to better preparedness and planning for the agricultural and water resource sectors. The report also emphasizes the significant influence of climate drivers on the monsoon’s behavior.