Weather Forecasting in India and Mission Mausam: IMD, Numerical Models, Doppler Radars, Bharat Forecast System, Supercomputers, Weather Modification and Early Warnings (UPSC Notes + PYQs)

Why forecasts matter

In October 1999, a super cyclone struck Odisha and killed nearly ten thousand people. In October 2013, Cyclone Phailin, of similar strength, hit almost the same coast, but fewer than fifty people died, because accurate forecasts allowed close to a million people to be evacuated in time. That contrast sums up the value of weather science. Good forecasts save lives in cyclones, floods, heatwaves and lightning, which kills more Indians every year than any other single natural hazard. They also save money: farmers time sowing and spraying, power grids plan for solar and wind output, airlines and ships plan routes, and cities prepare drains before heavy rain.

Yet India’s weather is among the hardest in the world to predict. The monsoon is shaped by the Himalayas, the Indian Ocean, El Niño and La Niña in the Pacific, the Indian Ocean Dipole and the Madden-Julian Oscillation. Tropical weather changes fast, and climate change is making extreme rain bursts, cloudbursts and heatwaves more frequent and more localised.

Who forecasts India’s weather

All except ISRO fall under the Ministry of Earth Sciences (MoES). IMD celebrated its 150th anniversary in January 2025, when the Prime Minister formally launched Mission Mausam.

How a forecast is made

A forecast starts with observations: temperature, pressure, humidity and wind from ground stations, weather balloons (radiosondes), ships, buoys, aircraft, radars and satellites. These are fed into numerical weather prediction models, which divide the atmosphere into a three-dimensional grid and solve the equations of fluid motion and heat at each point. The finer the grid, the more local the forecast, but the more computing power is needed. Results are then interpreted by forecasters and issued as impact-based warnings using a colour code: green, yellow, orange and red.

Forecasts are of several kinds: nowcasts for the next few hours, used for thunderstorms and lightning; short and medium range forecasts up to ten days; extended range forecasts for two to four weeks; and seasonal forecasts such as the monsoon outlook issued in April and June.

Mission Mausam: components

• Observations: dense networks of Doppler weather radars, wind profilers, radiosondes, automatic weather stations and rain gauges, aiming to cover the whole country, especially the Himalayas and the North-East.
• Computing: in September 2024 two High Performance Computing systems were commissioned: Arka at IITM Pune and Arunika at NCMRWF Noida, together about 20 petaflops.
• Better models: the Bharat Forecast System (BFS), launched in May 2025 and developed by IITM Pune, runs at about 6 km resolution, among the finest of any global operational model, and can give forecasts at the level of clusters of panchayats.
• AI and machine learning: blending physics-based models with AI for nowcasting and extreme events.
• Weather management research: a cloud chamber at IITM to study cloud physics, with long-term research on rain enhancement, hail and fog suppression and lightning control.
• Dissemination: forecasts to farmers, fishermen and disaster managers through apps such as Mausam, Meghdoot and Damini, and through panchayat-level weather services.

Earlier milestones

Impact-based forecasting

A forecast that says “heavy rain likely” is less useful than one that says “low-lying roads in these wards may flood after 4 pm; avoid travel”. IMD has moved to impact-based forecasts and risk-based warnings, combining weather predictions with data on exposure and vulnerability, such as population, crops, roads and drainage. Heat action plans in cities like Ahmedabad, launched after the 2010 heatwave, show how a forecast linked to a ready plan of cool shelters, water points and hospital readiness can cut deaths sharply. Mission Mausam aims to make such linked warnings the norm across districts.

Why the mission matters

• Disaster risk reduction: India supports the UN’s Early Warnings for All goal by 2027 and the Sendai Framework.
• Agriculture: about half of farmland is rain-fed; block-level agro-advisories can reduce losses.
• Energy transition: solar and wind need accurate short-term forecasts to balance the grid.
• Health: heat action plans depend on heatwave forecasts.
• Urban floods: cities like Mumbai, Chennai and Bengaluru need high-resolution rainfall nowcasts.
• Neighbourhood: IMD’s regional role lets India provide forecasts and warnings to neighbours in South Asia.

Challenges

• Observation gaps: radar coverage in hilly regions remains thin, and cloudbursts there are very local.
• Extreme events: models still struggle with sudden, intense, small-scale rainfall, as seen in the Wayanad landslides (2024) and Himalayan flash floods.
• Last mile: warnings often fail to reach the farmer or fisher in a usable language and time.
• Skills: India needs more atmospheric scientists, data scientists and forecasters.
• Weather modification: cloud seeding has uncertain results and raises ethical and legal questions.
• Data sharing: State agencies, private weather firms and IMD use different networks; standards and sharing are weak.

Way forward

Complete radar and automatic weather station coverage, especially in the Himalayas. Combine physics-based models with AI, as global centres now do, while building Indian datasets. Make warnings impact-based and hyper-local, delivered in local languages through mobile, radio and panchayats. Train forecasters and create career paths in atmospheric science. Set clear rules for private weather services and data sharing. Fund long-term research on monsoon variability and climate change, so that India not only forecasts but also anticipates how its weather is changing.

PYQ trend

Prelims has asked about the Bharat Forecast System and about cyclones and monsoon factors. Mains GS-I asks about cyclones, monsoon and climate-smart agriculture; GS-III about disaster management.

Mission Mausam: UPSC angle

Mission Mausam UPSC PYQs (Prelims)

Questions UPSC has actually asked, from the official papers. Pick an option to check yourself.

Mains PYQs on this topic

No UPSC Mains question from 2023-2026 is directly on this topic. Older papers (2013-2022) will be added as the Mains bank grows.

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Image: IM3847, Wikimedia Commons, CC BY-SA 4.0