Why Do Cyclones Only Form Over the Sea? Cyclone Arnab, Explained — and How to Stay Safe

Short answer: Cyclones only form over the sea because a cyclone is a heat engine that runs on warm seawater — an ocean surface of roughly 26.5°C or warmer. The warm water evaporates, the vapour rises and condenses, and that released heat powers the storm while the Earth’s spin twists the inflowing air into a spiral around a calm eye. Land has no warm sea to feed it, so a cyclone weakens after landfall. Cyclone Arnab proved the point on 28 October 2026: it was born over the warm Bay of Bengal and crossed the Andhra Pradesh coast near Yanam and Kakinada between 2 am and 4 am, with winds gusting to 150 km/h. To stay safe in a cyclone: leave when officials tell you to, stay away from windows, switch off the main power if water enters, avoid fallen wires, drink boiled water, and do not step out when the eye goes calm — wait for the official all-clear.

The misconception: storms just “come from” the sea

Most of us picture a cyclone the way we picture rain: weather that happens to arrive from over the water. It sounds like geography. It is actually chemistry and plumbing.

A cyclone is not something the sea sends. It is something the sea runs. Cut the fuel line and the engine stalls.

The real answer: a heat engine with a fuel line

Here is the machine, in four parts.

1. Fuel. When the sea surface is about 26.5°C or warmer, huge amounts of water evaporate. That moist air is the fuel.
2. Combustion. The moist air rises. Higher up it cools, the vapour condenses into cloud and rain, and condensation releases heat. That heat warms the air further, which makes it rise faster, which pulls in more moist air from below. The storm is now feeding itself.
3. The twist. Air rushes inwards towards the low-pressure centre. Because the Earth is spinning, that inflowing air is deflected and curls into a spiral (the Coriolis effect). In the northern hemisphere it turns anticlockwise.
4. The eye. At the very centre, air sinks instead of rising. That is the calm, sometimes clear, eye — surrounded by the eyewall, where the worst winds live.

Now move that engine over land. No warm water, no evaporation, no fuel. Friction from hills, trees and buildings also slows the wind. The storm still dumps enormous rain as it decays, but it is running on its last tank. That is why a cyclone is strongest at the coast and fades inland.

Hurricane, typhoon, cyclone: one storm, three passports

They are the same storm. It is called a hurricane in the Atlantic and eastern Pacific, a typhoon in the western Pacific and a cyclone in the Indian Ocean. The storms that do form over land in the United States are tornadoes — a different animal entirely: a few hundred metres wide, lasting minutes. A cyclone is hundreds of kilometres wide and lasts days.

Why India’s east coast, and why now

Why the east. The Bay of Bengal is warmer than the Arabian Sea, so it supplies more fuel. It is also shaped like a funnel, which steers storms onto the coasts of Odisha, Andhra Pradesh, Tamil Nadu, West Bengal and Bangladesh. The west coast gets cyclones too, just less often.

Why October and November. During the monsoon, strong winds high in the atmosphere blow across developing storms and tear their tops off before they can organise. After the monsoon withdraws, those upper winds ease — but the Bay of Bengal is still hot from summer. Full fuel tank, no one cutting the engine. That window gave India Cyclone Phailin (October 2013), Cyclone Hudhud (October 2014), Cyclone Titli (October 2018) and now Cyclone Arnab (October 2026).

The wry twist: the wind gets the headlines, the water does the killing

Every cyclone report leads with the wind speed. It is the number that looks most dramatic on a screen. But historically, the bigger killer is the storm surge — the wall of seawater a cyclone shoves onto a low coast — along with the flooding that follows.

And here is the part that should give everyone hope. Compare two very strong storms that hit the same state:

• The 1999 Odisha super cyclone: about 10,000 people died.
• Cyclone Phailin, Odisha, 2013: about 1 million people were evacuated in advance, and fewer than 50 died.

Odisha’s coast did not get gentler between 1999 and 2013. The difference was preparation: forecasts, shelters, and the decision to move people before the water came. Nature sets the size of the storm. People decide most of the damage.

Cyclone Arnab: what we know (as of 28 October 2026)

• Landfall: near Yanam–Kakinada, Andhra Pradesh, between about 2 am and 4 am on 28 October 2026.
• Wind: gusting to about 150 km/h.
• Evacuation: about 89,000 people moved to relief camps in Andhra Pradesh.
• Response: NDRF teams deployed in Andhra Pradesh and Odisha; ₹27 crore released to 20 districts.
• Travel: flights by Air India and IndiGo were cancelled, and train services in the region were disrupted.
• Helplines: 112 (national emergency) and 1070 (Andhra Pradesh disaster control room). Verify current numbers on the APSDMA website before relying on them.

No final death toll has been confirmed; we will not guess one.

What to actually do

If you are in the storm’s path

• Leave when officials tell you to. Relief camps exist because evacuation is what turned 1999 into 2013.
• Stay away from windows and glass doors. Stay in the strongest inner room.
• If water enters your home, switch off the main power at the mains.
• Stay away from fallen electric wires and anything touching them, including puddles.
• Drink boiled or sealed water only; floodwater contaminates supply.
• When the eye passes and it goes calm, do not go out. The other half of the storm is coming, often with wind from the opposite direction.
• Wait for the official all-clear before returning or travelling.

Your money, after the storm

• Train cancelled by Indian Railways: you get the full fare back. E-tickets are refunded automatically; counter tickets must be surrendered within 3 days.
• Flight cancelled: the airline must offer an alternate flight or a full refund. It does not owe extra compensation, because weather is outside its control.
• Car in floodwater: do not try to start the engine. Cranking a flooded engine causes the damage most motor policies refuse to cover. Have it towed. An engine-protect add-on is what covers water damage to the engine — check whether your policy has one.

The last word

A cyclone is enormous, but it is not mysterious, and it is not unbeatable. It needs a warm sea; it dies on land; and the death toll depends more on our readiness than on its wind. To everyone in coastal Andhra Pradesh and Odisha facing Arnab tonight: you are not alone. Thousands of rescuers, neighbours and strangers are on your side of the storm.