Synopsis
The India Meteorological Department forecasts that the seasonal rainfall during the Southwest Monsoon from June to September in 2025 is expected to exceed 104 percent of the Long Period Average, indicating a likely above-normal season. Updated forecasts will be available at the end of May.Key Takeaways
- IMD predicts above-normal rainfall for the Southwest Monsoon in 2025.
- Forecast indicates 105 percent of the Long Period Average.
- Neutral ENSO conditions expected to prevail.
- Significant probability (59%) for above normal rainfall.
- Updated forecasts will be issued end of May.
New Delhi, April 15 (NationPress) The anticipated seasonal rainfall during the Southwest Monsoon (June to September) across the nation this year is projected to be above normal, exceeding 104 percent of the Long Period Average (LPA), according to an announcement made by the India Meteorological Department (IMD) on Tuesday.
Specifically, the overall seasonal rainfall across the country, derived from both dynamical and statistical forecasting models, is likely to reach 105 percent of the LPA, with a model error margin of plus/minus 5 percent, as stated in a communiqué from the Earth Sciences Ministry. The LPA for seasonal rainfall from 1971 to 2020 stands at 87 cm.
The IMD indicated that neutral El Nino-Southern Oscillation (ENSO) conditions currently prevail over the equatorial Pacific region; however, the atmospheric circulation characteristics resemble those typical of La Nina conditions. The latest forecasts from the Monsoon Mission Climate Forecast System (MMCFS) and other climate models suggest that the Neutral ENSO conditions are expected to persist throughout the monsoon season.
Moreover, the weather agency noted the presence of neutral Indian Ocean Dipole (IOD) conditions over the Indian Ocean, with recent climate models indicating these conditions are likely to continue during the Southwest Monsoon.
It was also observed that snow cover in the northern hemisphere and Eurasia for the past three months (January to March 2025), which generally has an inverse correlation with Indian summer monsoon rainfall, was below normal.
The IMD has issued a five-category probability forecast for the seasonal (June to September) rainfall across the country, indicating a significant likelihood (59 percent) of the Southwest Monsoon rainfall falling into the above normal category or higher (excess), which is greater than 104 percent of the LPA.
The forecast estimates a 30 percent probability for normal monsoon conditions, a 9 percent probability for below normal conditions, and a 2 percent probability for a deficient monsoon.
The IMD plans to release updated forecasts for monsoon season rainfall in the last week of May, adhering to its established practice since 2003.
Since then, the IMD has provided the operational long-range forecast (LRF) for the Southwest Monsoon seasonal rainfall (June-September) averaged over the entire country in two phases—initially in April and then at the end of May.
In 2021, the IMD adopted a new methodology for providing monthly and seasonal operational forecasts for the Southwest Monsoon rainfall across the nation by revising the existing two-stage forecasting approach. This new strategy employs both dynamical and statistical forecasting systems. The Multi-Model Ensemble (MME) forecasting system utilizes coupled global climate models (CGCMs) from various global climate prediction centers, including the IMD’s Monsoon Mission Climate Forecast System (MMCFS).
According to the revised LRF strategy, the first-stage forecast released in mid-April includes quantitative and probabilistic forecasts for the country overall, along with the spatial distribution of probabilistic forecasts for the tercile categories (above normal, normal, and below normal) of the seasonal (June-September) rainfall across the nation.
The second-stage forecast, issued around the end of May, provides an update for the seasonal rainfall forecast issued in April, along with probabilistic forecasts for seasonal rainfall in four homogeneous regions of India (northwest India, central India, south Peninsula, and northeast India) and the monsoon core zone (MCZ). Additionally, quantitative and probabilistic forecasts for the country as a whole, as well as the spatial distribution of probabilistic forecasts for the tercile categories (above normal, normal, below normal) of June rainfall across the nation, are also included in the second-stage forecast.
Following these forecasts, monthly rainfall predictions are released at the end of June, July, and August for the upcoming month. Furthermore, quantitative and probabilistic forecasts for the entire country and the spatial distribution of probabilistic forecasts for the tercile categories for the latter half of the season’s rainfall are provided around the end of July, along with the forecast for August.
