Cyclones that threaten Chennai are named by the India Meteorological Department from a fixed list of 169 names contributed by 13 countries, and IMD warns the coast in four stages that begin about 72 hours before bad weather is expected. Knowing those stages is more useful than any track map shared on social media.
October to December is the main cyclone season for the Tamil Nadu coast, and Chennai’s two most recent hard lessons, Vardah in 2016 and Michaung in 2023, were both December storms. Here is how storms get their names, how IMD’s warnings escalate and what those two cyclones taught the city.
How Bay of Bengal cyclones are named
Names come from a list agreed by the 13 member countries of the WMO/ESCAP Panel on Tropical Cyclones. A new list of 169 names, 13 from each country, was issued in 2020, the World Meteorological Organization says. India’s IMD, as the regional specialised meteorological centre in New Delhi, assigns the next name on the list when a system becomes a cyclonic storm.
The rules are strict. Names must be neutral on politics, religion, culture and gender, must not offend anyone, and can be no longer than eight letters. A used name is retired and never repeated.
The list is arranged so that names are used country by country in turn. That means the origin of a name tells you nothing about where a storm will go. A name proposed by Thailand or Oman is as likely to reach the Tamil Nadu coast as one proposed by India.
A system is only named once it reaches cyclonic storm strength. Weaker systems are called depressions or deep depressions and carry only a number. A depression can still bring very heavy rain, so do not wait for a name before taking warnings seriously.
IMD’s four warning stages
For the coast, IMD uses a four-stage warning system:
- Pre-cyclone watch, about 72 hours ahead, sent to senior central and state officials.
- Cyclone alert (yellow), at least 48 hours before bad weather reaches the coast.
- Cyclone warning (orange), at least 24 hours ahead, updated every three hours.
- Post-landfall outlook (red), at least 12 hours before landfall, covering how the storm will behave over land.
Fishermen’s warnings are issued separately and usually start earlier. The public is warned through state officials, All India Radio and Doordarshan, and today through apps and SMS alerts as well.
Vardah, December 2016: the wind storm
Vardah crossed the coast close to Chennai on 12 December 2016 and is remembered for its wind rather than its rain. Trees came down across the city and suburbs, blocking roads and crushing parked vehicles. Overhead power lines and poles were damaged so widely that some areas waited days for supply to return, and mobile networks failed when towers lost power.
The lessons were practical. Large, shallow-rooted avenue and compound trees were the biggest single hazard, and households that had stored water, cash and charged batteries in advance coped far better in the days after. Many residents’ associations now have overgrown trees pruned before the monsoon for this reason.
Michaung, December 2023: the rain storm
Michaung never crossed the Chennai coast. It moved slowly north, parallel to the shore, before making landfall in Andhra Pradesh. While it lingered offshore it dropped extreme rain on Chennai, and on 4 December 2023 large parts of the city and its suburbs were under water.
On 4 December, the Corporation opened 162 relief centres and NDRF teams were deployed across Chennai, Chengalpattu, Kancheepuram and Villupuram, The News Minute reported. Power was cut in flooded areas to prevent electrocution.
The lesson from Michaung is that a cyclone’s track matters less than how slowly it moves. A storm 100 km offshore can still dump more rain on Chennai than one that crosses the city.
What to do when a cyclone is forecast
- Follow the warning stage, not social media maps of possible tracks. For Chennai specifically, check the colour for Chennai district on IMD’s district warnings map.
- At the alert stage, stock water, food, medicines and charged batteries for three days.
- Tie down or bring in loose items on terraces and balconies.
- Park away from trees, hoardings and low streets.
- Stay indoors when the eye passes. The calm is temporary.
- After the storm, keep away from fallen wires and waterlogged streets until power is restored and the area has been checked.
Quick answers
Who names Bay of Bengal cyclones?
IMD assigns names from a list of 169 contributed by 13 countries through the WMO/ESCAP panel.
Are cyclone names reused?
No. Once used, a name is retired.
Is a depression less dangerous than a cyclone?
Not for rain. Depressions are not named, but they can still bring very heavy rain, so follow IMD’s district warnings whatever the system is called.
What colour is a cyclone warning?
Orange, issued at least 24 hours before bad weather reaches the coast.
Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.
