Chennai’s weather forecasts and rain warnings come from the India Meteorological Department’s Regional Meteorological Centre (RMC) at Nungambakkam, which covers Tamil Nadu, Puducherry and Karaikal. Its forecasting office runs a 24-hour line, 044-28246048, and publishes district warnings, nowcasts and a seven-day outlook on its official page. This explains how those forecasts are put together, not what the alert colours mean.
The timing matters. The northeast monsoon set in over Tamil Nadu on 15 October 2026, and the city’s main long-range radar was under repair only weeks earlier. Here is how the system works, what each radar does and which products are worth bookmarking.
A long history of storm warnings
Storm warning work for east coast ports from Kalingapatnam southwards moved to Chennai (Meenambakkam) in 1945, according to IMD’s own history. In 1969 a separate storm warning centre was set up at Nungambakkam to split marine warnings from aviation work, and the same year Chennai took over warnings for west coast ports from Karwar southwards. Today the centre also houses a Cyclone Warning Research Centre, which publishes cyclone track and rainfall atlases.
The radars watching the city
Radar is how forecasters see a rain band or a cyclone’s eye before it arrives. Chennai depends on two main units, both described by The Federal in September 2026:
| Radar | Where | What it does |
|---|---|---|
| S-band Doppler weather radar | Chennai Port Trust Centenary Building, about 53 m above sea level | Scans a 500 km radius for cyclones, rain bands and wind; working since February 2002, when it became India’s first Doppler weather radar |
| X-band radar | NIOT campus, Pallikaranai | Shorter range, finer detail; the city’s nowcasting radar |
Radars at Sriharikota and Karaikal add coverage, along with satellite imagery and computer models, DT Next noted.
The port radar is old. In late September 2026 it was under maintenance for slew-ring work and running in trial mode, and the RMC’s head, Dr. Sivananda Damodara Pai, told The Federal that the repairs would be done within a week. A replacement S-band radar was to be installed in July 2026, but the supplier now does not expect it before July 2027 because one spare part has to come from the United States. Even with a radar down, IMD can still issue warnings using other radars, satellites and models.
From observation to warning
A forecast at RMC Chennai passes through roughly these stages:
- Observe. Surface observatories, a state network of automatic weather stations, radar sweeps, satellite pictures and lightning data feed in round the clock. The public can also submit observations through a portal on the RMC site.
- Model. National weather models run on IMD’s and the Ministry of Earth Sciences’ supercomputers give a first guess for the coming days.
- Judge. Duty forecasters compare model output with what the radar and satellites actually show, and adjust for local effects such as sea breeze timing along the coast.
- Issue. The result goes out as district-wise warnings, station-wise nowcasts for the next few hours, port and fishermen warnings, and impact-based forecasts that say what the weather may do on the ground.
Keeping the port radar alive has needed improvisation. After a bull-gear failure left spare parts scarce, ISRO’s ISTRAC and local engineering workshops rebuilt a unit in 2022 to keep the 2002 radar running, The Federal reported.
Nowcasts are the most useful for daily plans in the monsoon. They come from radar and cover the next few hours, so they catch a thunderstorm building over the city that a morning forecast could not.
What is changing
The Union Cabinet approved Mission Mausam on 11 September 2024 with an outlay of ₹2,000 crore over two years, to bring next-generation radars, satellites, supercomputers, better models and AI tools into forecasting, according to PMIndia. The Federal reported that the Centre has listed Kanniyakumari, Tiruchi and Coimbatore as radar sites under the mission, and that the state disaster agency planned radars at Yercaud and Ramanathapuram.
Products worth bookmarking
- Chennai city nowcast and seven-day forecast on the RMC page.
- District-wise warnings and the seven-day forecast and warnings for Tamil Nadu and Puducherry.
- 24-hour rainfall by station, plus a 24-hour rainfall forecast in English, Tamil and Hindi.
- Radar and satellite images, including a satellite view with lightning.
- Damini, IMD’s lightning warning app.
Media queries go to Dr. V. R. Durai, Scientist-F (044-28246037), and weather data requests to Dr. Arvind Kumar, Scientist-D (044-28246072), as listed on the RMC page.
Quick answers
Where is IMD’s Chennai office?
The Regional Weather Forecasting Centre is at Nungambakkam, Chennai 600 006. The 24×7 number is 044-28246048.
Which radar covers Chennai?
The S-band Doppler radar at Chennai Port for long range, and the X-band radar at NIOT, Pallikaranai, for short-range nowcasts.
When will the new Chennai radar come?
The replacement S-band radar is not expected before July 2027, The Federal reported in September 2026.
What is a nowcast?
A short-range warning for the next few hours based mainly on radar. RMC Chennai issues them district-wise and station-wise.
Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.
Sources
- Regional Meteorological Centre Chennai (IMD)
- Historical perspective of cyclone warning work (IMD RSMC New Delhi)
- Cabinet approves Mission Mausam (PMIndia)
- Iran war delays Chennai’s new cyclone radar; S-band DWR down (The Federal)
- Chennai weather radar faces glitch ahead of northeast monsoon (DT Next)
