India Meteorological Department (IMD)

The India Meteorological Department (IMD) is the national meteorological service of the Republic of India and the principal government agency for all matters relating to meteorology, seismology, and allied subjects. It was established in 1875 in the aftermath of two catastrophic events: the tropical cyclone that struck Calcutta in October 1864 and the monsoon-failure famines of 1866 and 1871, which exposed the absence of a unified system for collecting and analysing weather data across British India. The first Imperial Meteorological Reporter, Henry Francis Blanford, was appointed to coordinate observatories that had previously operated under disparate provincial administrations. The department's headquarters, originally in Calcutta, moved to Shimla, then Pune, and finally to Mausam Bhavan in New Delhi. Today IMD functions as a subordinate office of the Ministry of Earth Sciences (MoES), a status it acquired when the ministry was created in 2006; before that it reported through the Department of Science and Technology and, in earlier decades, the Ministry of Transport and aviation portfolios.

The department's core procedural function is the issuance of weather forecasts and warnings on graduated time horizons. IMD generates nowcasts (up to three hours), short-range forecasts (up to three days), medium-range forecasts (up to ten days), and extended-range and seasonal outlooks, the last including its closely watched Long Range Forecast of the southwest monsoon, issued in April and updated in June. Observations feed in from a national network of surface observatories, automatic weather stations, upper-air radiosonde stations, Doppler Weather Radars, and data from the INSAT geostationary satellite series operated jointly with the Indian Space Research Organisation. These inputs are assimilated into numerical weather prediction models run on supercomputers managed by the National Centre for Medium Range Weather Forecasting and the Indian Institute of Tropical Meteorology, both MoES institutions that work in tandem with IMD's forecasting divisions.

Beyond routine forecasting, IMD discharges specialised mandates assigned by international and domestic bodies. It is one of six Regional Specialised Meteorological Centres (RSMC) designated by the World Meteorological Organization for tropical cyclones, with responsibility for the north Indian Ocean basin encompassing the Bay of Bengal and the Arabian Sea; in this role it names cyclones and issues advisories to thirteen member countries including Bangladesh, Myanmar, Oman, and the Maldives. IMD also operates the National Seismological Network for earthquake monitoring, hosts the agrometeorological advisory service for farmers, and provides aviation meteorology at airports. Its colour-coded warning system—green, yellow, orange, and red—translates impact-based forecasting into actionable alerts for district administrations and the National Disaster Management Authority.

Recent named instances illustrate the department's operational weight. Ahead of Cyclone Fani in May 2019, IMD's RSMC New Delhi issued precise landfall forecasts for the Odisha coast that enabled the state government to evacuate roughly 1.2 million people, an exercise praised by the United Nations as a model of early warning. In the May 2020 Cyclone Amphan and the 2021 cyclones Tauktae and Yaas, IMD bulletins again guided evacuations across West Bengal, Gujarat, and Odisha. In recognition of its 150th anniversary, the Government of India marked IMD's sesquicentennial in January 2025, and the department under Director General Mrutyunjay Mohapatra has pursued the "Mission Mausam" initiative announced by the Union Cabinet in 2024 to expand radar coverage and improve forecast resolution.

IMD must be distinguished from adjacent institutions with which it is frequently confused. It is not the same as the Indian Space Research Organisation (ISRO), which builds and operates the satellites whose data IMD ingests but which does not issue forecasts; nor is it the Central Water Commission, which handles flood forecasting on river systems, though the two coordinate during monsoon flooding. IMD is also distinct from the Indian Institute of Tropical Meteorology, a research body, and from the National Centre for Medium Range Weather Forecasting, which develops models. Internationally, IMD's RSMC role differs from that of a WMO World Meteorological Centre; it is a regional, basin-specific designation tied to cyclone advisories rather than global model output.

The department has drawn periodic controversy over forecast accuracy, particularly its seasonal monsoon predictions, which directly influence agricultural policy, crop insurance, and commodity markets. Critics have noted instances where the April Long Range Forecast diverged significantly from realised rainfall, prompting IMD to abandon its older sixteen-parameter statistical model in favour of dynamical and ensemble approaches and to introduce probabilistic categories. The shift toward impact-based and location-specific warnings, rather than purely meteorological statements, reflects a wider international trend but has raised questions about coordination with state disaster authorities, who act on the colour codes. Heatwave forecasting has gained prominence as Indian summers intensify, with IMD declaring heatwave thresholds and issuing health advisories.

For the working practitioner—whether a civil-services aspirant, a disaster-management officer, or a foreign-desk analyst tracking South Asian climate risk—IMD is the authoritative single source for India's official weather and cyclone data, and its bulletins carry legal and administrative standing for triggering relief mobilisation. Understanding its institutional location within the Ministry of Earth Sciences, its WMO regional obligations, and the distinction between its forecasting and research functions is essential for interpreting Indian climate governance. As monsoon variability and cyclone intensity respond to a warming Indian Ocean, the department's forecasts increasingly shape food security, fiscal planning, and the regional diplomacy of early-warning data-sharing across the Bay of Bengal littoral.