Cyclone preparedness in India: how IMD tracks storms, what landfall really means, and how coastal states get ready

How a cyclone is born over warm water

A tropical cyclone is a heat engine. It starts when sea surface temperatures rise above roughly 26.5 degrees Celsius, the lower atmosphere holds enough moisture, vertical wind shear stays low, and some initial rotation gives the system a spin. Warm, moist air rises from the sea surface, creating low pressure below; surrounding air rushes in, rises in turn, and releases latent heat as its water vapour condenses into clouds. That heat release strengthens the updraft, the winds organise into a spiral, and a depression can deepen, step by step, into a cyclonic storm. In the Northern Hemisphere the Coriolis effect makes the circulation anticlockwise, which is why Indian cyclones spin the opposite way to those south of the equator.

India's geography makes this a recurring threat. The country has roughly 7,500 kilometres of coastline, and the North Indian Ocean has two distinct cyclone seasons rather than one: a pre-monsoon window from April to early June and a post-monsoon window from October to December. During the southwest monsoon itself, strong vertical wind shear tears developing systems apart, which is why July to September is comparatively quiet. The post-monsoon window tends to produce the more intense storms, because the sea has absorbed heat all summer and upper-atmosphere conditions turn favourable once the monsoon trough shifts south. Cyclone Arnab, which formed over the Bay of Bengal in late October 2026, is a textbook post-monsoon case: it grew from a low-pressure area on 24 October into a very severe cyclonic storm within about three days.

The IMD ladder: from depression to super cyclone

The India Meteorological Department, through its Regional Specialised Meteorological Centre in New Delhi, classifies cyclonic disturbances by maximum sustained surface wind speed. The weakest systems are a low-pressure area, then a depression, with winds of 31 to 49 kilometres per hour, and a deep depression, at 50 to 61 kilometres per hour. Once sustained winds reach about 62 kilometres per hour, the system becomes a cyclonic storm and earns a name. Above that come the severe cyclonic storm, the very severe cyclonic storm, the extremely severe cyclonic storm, and finally the super cyclonic storm, with sustained winds above about 221 kilometres per hour. Arnab's very severe rating corresponds to sustained winds of roughly 119 to 165 kilometres per hour, which is why it was described as a powerful but not top-tier storm.

Names come from a rotating list contributed by 13 countries in the region, including India, Bangladesh, Pakistan, Sri Lanka, Myanmar, the Maldives, Oman, Thailand, Yemen, the United Arab Emirates, Iran, Qatar and Saudi Arabia, with 169 names on the current list. Arnab was contributed by Bangladesh; in Bengali the word means ocean or sea. The name says nothing about strength or destination: a storm named from one country's list entry can strike another country's coast, and a system that never reaches cyclonic storm strength never gets a name at all. Naming exists so that forecasters, officials and the public can follow one system without confusing it with another, which matters when two disturbances are active at once.

What the landfall process actually means

Landfall is often reported as if it were a single moment, but it is a process that takes hours. It begins when the cyclone's outer edge, and then its eye wall, starts crossing the coast, and it ends only when the centre of the storm has moved fully over land. During that window, the strongest winds are usually felt in the storm's forward flank, and conditions can change violently as the eye passes: a brief calm inside the eye can fool people into thinking the storm is over, when in fact the other side of the eye wall is about to arrive with winds from the opposite direction. Arnab crossed the Andhra Pradesh coast in the early hours of 28 October 2026, tracking between Bapatla and Visakhapatnam near Yanam, with sustained winds of 125 to 135 kilometres per hour and gusts reaching 150 kilometres per hour.

Crossing land also begins the storm's decay, but slowly. Cut off from warm ocean water, its energy source, and disrupted by friction over land, a cyclone weakens into a depression and then a remnant low. That weakening does not end the danger. Arnab's remnants were forecast to carry heavy to very heavy rainfall inland across Andhra Pradesh, southern Odisha, Telangana and potentially Chhattisgarh for days after landfall, and the India Meteorological Department warned of a storm surge of 1.5 to 2.5 metres above the normal tide inundating low-lying areas in the hours after the crossing. Inland flooding, not wind, is often what causes the most damage once a cyclone has moved away from the coast, which is why warnings continue well after the headlines about landfall fade.

The three ways a cyclone kills: wind, rain and surge

A cyclone attacks in three ways, and they peak at different times. Wind tears roofs, uproots trees, snaps power lines and turns loose objects into projectiles; the damage rises steeply with wind speed, which is why the difference between a severe and a very severe storm matters so much for housing. Rain falls in enormous quantities over a wide area, swelling rivers, breaching embankments and flooding towns far from the coast. And storm surge, the abnormal rise of sea water pushed ashore by the storm's winds, has historically been the biggest killer of the three, because it can inundate villages kilometres inland with little warning for anyone who stayed behind.

The Bay of Bengal is especially dangerous for surge. Its northern waters are shallow, which pushes surge water further inland, and its coastline is densely populated, so a surge that would flood empty marshland elsewhere can drown whole villages here. The 1999 Odisha Super Cyclone, with sustained winds of 260 to 270 kilometres per hour, killed nearly 10,000 people, many of them through a massive surge that inundated settlements far from the shore. After that storm, outbreaks of diarrhoea and cholera spread through displaced populations, and saltwater intrusion ruined farmland and contaminated freshwater sources. Any honest account of cyclone risk has to count these second-order effects alongside the wind: a storm's death toll is decided as much by water and disease as by the speed of its winds.

How warnings travel from satellite to village

The warning chain starts with the IMD's cyclone warning centres, seven of which track systems over the North Indian Ocean using satellites, coastal radars, buoys and computer models. Their bulletins give the storm's position, intensity, likely track, and the expected point and time of landfall, together with associated rainfall, winds and storm surge. Warnings are issued in a four-stage colour-coded scheme of green, yellow, orange and red, depending on severity and on how close the storm is to landfall, so that a district officer, a television viewer and a fisherman all hear the same graded message. The IMD also issues advisories telling fishers to stay ashore, and during Arnab that advisory was extended through at least 29 October.

Getting the forecast right is only half the job; the other half is last-mile delivery. Odisha's Early Warning Dissemination System, installed along its 480-kilometre coastline in April 2018, uses 122 coastal watchtowers equipped with sirens and mass-messaging capability to reach fishing communities and low-lying villages that television and newspapers miss. During Arnab, Andhra Pradesh dispatched emergency alerts to millions of mobile phones across its coastal districts, while Odisha's district administrations went village by village. The same week also showed the system's vulnerability to noise: Odisha's Special Relief Commissioner had to warn formally on 26 October that people spreading false disaster alerts on social media could face legal action, and asked media outlets to verify weather information against official IMD bulletins before publishing.

The evacuation machine: what the Odisha model changed

India's disaster management architecture was rebuilt after 1999. The Disaster Management Act of 2005 created the National Disaster Management Authority, headed by the Prime Minister, to lay down policy and coordinate the Centre, the states and the districts, and the National Disaster Response Force was built up as a dedicated rescue arm. On the ground, the National Cyclone Risk Mitigation Project, covering six coastal states with an outlay of about 2,059 crore rupees, funded multi-purpose cyclone shelters, coastal embankments, saline embankment strengthening and underground power cabling in vulnerable zones. Odisha alone built more than 900 multi-purpose cyclone shelters along its coast, two-storeyed structures designed to withstand extreme winds.

The results are visible in the death tolls. In 2019, Cyclone Fani, another extremely severe storm, struck the same Odisha coast as the 1999 super cyclone, but timely warnings and a planned large-scale evacuation moved about 1.2 million people into nearly 4,000 shelters, and the death toll in Odisha was kept to 64. Cyclone Phailin in 2013, of similar intensity to the 1999 storm, was likewise recognised by the United Nations as a global success story because mass evacuation kept deaths far below 1999 levels. Arnab followed the same template: more than 136,000 people were evacuated before landfall, 466 cyclone and flood shelters were activated in Odisha, 31 NDRF teams were deployed across five states and Yanam, and Andhra Pradesh identified about 570,000 people as directly vulnerable and opened more than 2,000 shelters across 20 districts. Schools were closed, trains were cancelled or diverted, and fishing boats were ordered to harbour, with 35 boats carrying 305 fishers taking shelter at Paradip Port.

After landfall: the second disaster

When the wind drops, the work changes rather than ends. Power and telecom restoration comes first, because without it nothing else can be coordinated: crews clear fallen trees, restring lines, and in the most vulnerable zones the newer underground cabling, funded under the cyclone mitigation project, is meant to fail less often. Roads must be cleared for relief trucks, drinking water supplies checked for contamination, and health teams watch for the waterborne diseases that followed the 1999 storm. Damage assessment teams fan out to count destroyed houses, damaged crops and dead livestock, because compensation and reconstruction money follows those lists, and state governments release emergency funds quickly: Odisha released 19 crore rupees for its affected districts during Arnab, with the largest share going to Ganjam.

The return home is itself a managed process. People are asked to wait for the official all-clear rather than walking back through flooded roads, fallen power lines and weakened structures, and schools and childcare centres stay closed for a day or two longer in the worst-hit districts, as they did in parts of Odisha and Andhra Pradesh after Arnab. Crops damaged by saltwater may not recover for a season, and fishing families lose days or weeks of income while boats are repaired and the sea remains rough. This is why disaster officials talk about the response in phases: the evacuation saves lives, but the weeks after landfall decide whether a coastal community recovers or slides backwards, and whether the next storm finds it stronger or weaker than before.

What still needs fixing

For all the progress, the gaps are well documented. Even with modern forecasting, the precise impact of a cyclone can usually only be pinned down within about 36 to 60 hours before landfall, which compresses evacuation logistics into a very short window, especially for remote fishing hamlets and island communities where last-mile communication still fails. Coastal infrastructure needs continual reinforcement, and the natural defences are under pressure: mangroves, coral reefs and sand dunes are the first line of protection against storm surge, yet they continue to be lost to construction and aquaculture, a trade-off between development and safety that no coastal state has fully resolved.

The pattern of risk is also shifting. The Bay of Bengal still produces roughly four cyclones for every one in the Arabian Sea, with 190 Bay storms against 73 Arabian Sea storms between 1990 and 2020, but the Arabian Sea is becoming more active, with Ockhi in 2017, Tauktae in 2021 and Biparjoy in 2023 putting Gujarat, Maharashtra, Goa, Karnataka and Kerala on higher alert than before. The frequency of very severe cyclonic storms has risen by about one per decade over the past two decades even as the total number of cyclones has declined, meaning fewer but more intense storms, and warming seas are enabling rapid intensification, in which a storm jumps several categories in hours and compresses warning time further. The answer, as disaster researchers frame it, is not one more shelter but the whole system scaling together: better forecasts, protected mangroves, climate-resilient housing, regular community drills, and warnings that reach the last village before the wind does.

Editorial disclosure

This article was researched with AI assistance and reviewed by the publisher before publication. Report factual errors through our contact page.