India Meteorological Department

Also called: IMD · Topic: Atmosphere: Composition, Structure and Elements of Weather · NCERT: Class 7, Ch 2 "Understanding the Weather"; Class 7, Ch 3 "Climates of India"; Class 9, Ch 3 "Atmosphere and Climate"

Meaning

The India Meteorological Department (IMD) is India's national weather service. It was set up in 1875 and is now under the Ministry of Earth Sciences (MoES), with its headquarters at Mausam Bhawan, New Delhi. It observes the weather, forecasts it (including the monsoon) and issues warnings. As the RSMC New Delhi, it also tracks and names tropical cyclones over the North Indian Ocean.

It matters because good warnings save lives. Cyclone deaths fell from about 10,000 in 1999 to zero in 2020–2024 [2]. Farmers, fishermen, airlines and disaster managers in India all depend on its forecasts.

Explanation

Origin, home and identity

• Why IMD was created:
• A very strong tropical cyclone hit Calcutta in 1864.
• The monsoon then failed in 1866 and 1871.

• These disasters showed India needed one central weather service. In 1875, all weather work came under one authority [2].

• Headquarters: first at Calcutta. Now at Mausam Bhawan, New Delhi.

• Parent ministry: MoES, formed in 2006.
• Motto: adityat jayate vrishti ("from the sun arises rain"). It comes from the Manusmriti.

• The science behind it: the sun heats the oceans → water evaporates → the vapour rises, cools and condenses → it rains.

• First monsoon forecast: 1886, by Henry Blanford.

• "Firsts" [2]:
• IMD was the first organisation in India to have a message-switching computer, used to share weather data with other countries.

• With INSAT, India became the first developing country to have its own geostationary satellite that watches the weather all the time, especially for cyclone warnings.

• 150 years: the Prime Minister attended the 150th Foundation Day on 14 January 2025 at Bharat Mandapam, New Delhi. A postage stamp, a coin and the IMD Vision-2047 document were released [2].

What IMD does

Function	What it means
Observations	Measuring temperature, pressure, wind, humidity and rain at stations across India
Forecasts	From a few hours ahead up to a whole season
Monsoon forecast	A long-range forecast of June–September rain, issued since 1886
Cyclone warnings	Given as RSMC New Delhi for the North Indian Ocean
Agromet advisories	Weather-based advice to farmers on sowing, irrigation and spraying
Aviation services	Weather reports for airports and flights
Heat-wave warnings	Alerts for dangerously hot days, mostly in north-west and central India

• RSMC (Regional Specialised Meteorological Centre): a centre chosen by the WMO (World Meteorological Organization) to lead cyclone warnings for one region.
• Forecast time ranges:
• Nowcast: the next few hours (thunderstorms, lightning)
• Short range: 1–3 days
• Medium range: 3–10 days
• Extended range: up to 4 weeks

• Seasonal: a whole season, such as the June–September monsoon

• Nowcast models [2]:

• HRRR (High-Resolution Rapid Refresh) for rainfall and radar reflectivity (how strongly rain shows up on radar)

• EWRF (Electric Weather Research and Forecasting) for lightning density and total rainfall

• Colour-coded warnings, issued district by district:

• Green: no warning
• Yellow: be aware
• Orange: be prepared

• Red: take action

• Impact-based forecasting: the warning says what the weather will do (for example, "roads may flood"), not only what it will be. IMD has used it since 2019, together with the Common Alerting Protocol (a standard alert format that any phone or TV system can send out) [2].

How a forecast is made

Step 1. Collect observations

• AWS (automatic weather station): a machine that measures weather and sends the data by itself. IMD has built its own AWS since 2000 [2].
• Radiosonde: an instrument box carried up by a balloon. It measures temperature, humidity and pressure at different heights.
• Doppler weather radar (DWR): sends out radio waves that bounce off raindrops. This shows where rain is falling and how fast the wind is moving it.

• The network grew from 15 (2014) to 39 (2023), and the land area it covers grew by about 35% [2].

• Ships and buoys take readings over the sea.

• Satellites: INSAT-3D, INSAT-3DR and INSAT-3DS.
• INSAT-3DS was launched on 17 February 2024 on GSLV-F14 from Sriharikota. MoES paid for the whole mission [4].
• It sits in a geostationary orbit (about 36,000 km above the equator, moving at the same speed as the Earth turns), so it always watches the same part of the Earth [4].

• It carries a 6-channel Imager, a 19-channel Sounder, a Data Relay Transponder and a Satellite Aided Search & Rescue transponder [4].

• Instrument change: by 2023, every mercury barometer at IMD's Class I observatories had been replaced with a digital one. Mercury is poisonous, and the UNEP Minamata Convention controls its use [2].

• Public reports: a web page for public weather reports started in January 2021. The "Public Observation" app followed on 14 January 2022 [2].

Step 2. Run computer models

• NWP (numerical weather prediction): the atmosphere is split into a 3-D grid of boxes, and physics equations work out how each box will change over time.
• Supercomputers: Pratyush and Mihir (from 2018); Arka (at IITM Pune) and Arunika (at NCMRWF Noida), from 2024 [5].
• Resolution (the size of one grid box): until Mission Mausam, India's NWP models worked at 12 km [3]. The Bharat Forecast System, built by IITM Pune and launched in 2025, works at about 6 km [5].

Step 3. Issue the forecast

• Forecasts go out through bulletins, apps, websites and SMS.
• Mausamgram, an interactive forecast for any location, was released on 15 January 2024 [2].
• Overall forecast accuracy was 40% better in 2023 than in 2014 [2].

Programmes that upgrade IMD

• National Monsoon Mission (2012): set up by MoES and led mainly by IITM Pune. It moved monsoon forecasting from statistical models (which look only at past patterns) to dynamical models (physics-based models of the atmosphere and ocean).
• Mission Mausam:
• Approved by the Union Cabinet on 11 September 2024 [6], with Rs 2,000 crore for two years [3]. Launched on 14 January 2025 [2].
• Phase I: 2024–26. Phase II: 2026–31 [3].
• Goal: a "Weather-ready and Climate-smart" Bharat [3].
• Targets include 50 DWRs, 60 radiosonde/radiowind stations, 100 disdrometers (instruments that measure raindrop size), 10 wind profilers (radars that measure wind at many heights), 25 radiometers, 10 marine AWS, AI/ML tools and a GIS-based Decision Support System (a map-based computer system for getting forecasts to users) [3].
• It includes cloud seeding research: particles such as silver iodide or salt are sprayed into clouds → water vapour condenses on them → the drops grow heavy and fall as rain. It also covers fog dispersal and hail suppression [3].
• Expected outcomes: nowcasts every 1 hour instead of every 3 hours, short- and medium-range accuracy up by about 5–10%, and forecasts down to Panchayat level (5–6 km) [3].

Where it occurs

• Headquarters: Mausam Bhawan, New Delhi. Its first home was Calcutta (West Bengal).
• Region covered for cyclones: as RSMC New Delhi, IMD tracks and names cyclones over the Bay of Bengal and the Arabian Sea, the two parts of the North Indian Ocean.
• Cyclones forecast correctly: Phailin (2013), Hudhud (2014), Fani (2019), Amphan (2020), Tauktae (2021), Biparjoy (2023) and Dana (2024) [2].
• Coastal states where people are moved out before cyclones: mainly Odisha, Andhra Pradesh, West Bengal, Gujarat and Tamil Nadu.
• Heat-wave belt: mostly north-west and central India.
• NCERT example (Fig. 2.13, map of 19 May 2024): a heat wave over north-west India, with rain and thunderstorms in Tripura (north-east) and Lakshadweep (Arabian Sea).
• Sister bodies under MoES:
• IITM, Pune (Maharashtra): research and monsoon modelling [3]
• NCMRWF, Noida (Uttar Pradesh): numerical weather prediction and data assimilation (adding fresh observations into a model) [3]

• INCOIS, Hyderabad (Telangana): tsunami and high-wave alerts, and fishing-zone advice

• Satellite launch site: INSAT-3DS was launched from Sriharikota (Andhra Pradesh) [4].

• Other bodies that use IMD forecasts [3]: CWC (floods), GSI (landslides) and DGRE (avalanches).

Don't confuse with

• IITM Pune: a research institute that builds models (such as the Bharat Forecast System) and leads the Monsoon Mission. IMD is the agency that observes the weather and issues official forecasts and warnings.
• INCOIS Hyderabad: gives ocean services such as tsunami and high-wave alerts. IMD gives cyclone and weather warnings.
• National Monsoon Mission (2012) vs Mission Mausam (2024): the Monsoon Mission moved monsoon forecasting to dynamical models. Mission Mausam is a much wider upgrade, covering radars, AI/ML, 1-hour nowcasts and cloud seeding.
• Orange alert vs red alert: orange means "be prepared". Red means "take action". Yellow is only "be aware".

Prelims Hooks

• IMD was founded in 1875 at Calcutta. It is now at Mausam Bhawan, New Delhi, under MoES (2006). Its motto is adityat jayate vrishti, from the Manusmriti.
• The first monsoon forecast was issued in 1886 by Henry Blanford.
• RSMC New Delhi is a WMO-designated centre. It covers the North Indian Ocean (the Bay of Bengal and the Arabian Sea).
• Institute–city pairs: IITM is in Pune, NCMRWF in Noida and INCOIS in Hyderabad. Supercomputer pairs: Arka is at IITM and Arunika at NCMRWF (2024); Pratyush and Mihir date from 2018 [5].
• INSAT-3DS was launched on GSLV-F14 on 17 February 2024 from Sriharikota. It was fully funded by MoES, not by ISRO's own budget [4].
• Mission Mausam was approved in September 2024 with Rs 2,000 crore for 2 years and launched on 14 January 2025, IMD's 150th Foundation Day [2][3].

Mains Points

• Better forecasts reduce disaster risk (GS-III):
• More DWRs (15 → 39, 2014–2023), INSAT satellites and NWP models give more warning time [2].
• This means people can be moved out and ports closed in time. Cyclone deaths fell from about 10,000 (1999) to zero (2020–24) [2].

• This is a model for early warning for all under the Sendai Framework.

• Climate change makes forecasting harder:

• A warmer atmosphere holds more water vapour, which brings short, very heavy rain in one place. Floods and droughts can then hit nearby places at the same time.
• Cloudbursts, lightning and squalls are still the least understood weather events over India [3].

• The response is 6 km models, hourly nowcasts and impact-based, district-level warnings through Mission Mausam and BharatFS [3][5].

• Gaps and uses beyond disasters:

• IMD's work supports agromet advice for monsoon-dependent crops, aviation, heat-action plans and solar and wind power planning.
• Problems remain:
  • there are few observations over the oceans and the Himalaya
  • forecasts must reach fishermen and farmers in their own language
  • cloud seeding raises questions about whether it works, what it costs and whether it is ethical [3]

Related concepts

• Weather forecasting
• IMD colour-coded weather warnings
• Mission Mausam
• Bharat Forecast System

Read more

• Forecasting the weather: the IMD and India's forecasting system