Hurricane simulator
Send a hurricane of any strength into a real coastal city and watch its storm surge run over real terrain, with the wind zones and an estimated toll.
Open the hurricane simulatorWhat this simulator does
Pick a coastal city and set the sustained wind speed at landfall, from a weak category 1 at 120 km/h up to 320 km/h — beyond anything measured at landfall so far. The storm spirals in from the sea and makes landfall on the point you chose, and two things happen at once:
- The storm surge — seawater pushed ashore by the wind — floods the coast over real elevation data. It loses about a metre of height for every 2.5 km it travels inland, so low marshes and river deltas go under while a ridge or an embankment holds it back.
- The wind field spreads out from the eye: category 5, 4 and 3 winds close in, hurricane-force winds (above 119 km/h) tens of kilometres out, and gales for hundreds of kilometres.
The toll counts the people living on flooded ground, by water depth, plus the much smaller number killed by wind and flying debris. Like everywhere on this site, it assumes nobody evacuated.
The Saffir–Simpson categories
Hurricanes are ranked by their strongest sustained wind. The surge figures are the typical ranges from the old version of the scale; the National Hurricane Center dropped them in 2010 because real surges vary so much with storm size and the shape of the coast — but they are still a fair guide to what an open coast can expect.
- Category 1 — 119–153 km/h. Roofs and siding damaged, power out; surge about 1.2–1.5 m.
- Category 2 — 154–177 km/h. Major roof damage, many trees down; surge about 1.8–2.4 m.
- Category 3 — 178–208 km/h. The first "major" hurricane: well-built homes damaged, power and water gone for days; surge 2.7–3.7 m.
- Category 4 — 209–251 km/h. Roofs and outer walls torn off, the area cut off for weeks; surge 4–5.5 m.
- Category 5 — 252 km/h and above. Most wooden houses destroyed; surge over 5.5 m.
The historical storms under the slider do not use this table: each carries the surge that was actually measured, which is why Katrina, "only" a category 3, floods more than a textbook category 5.
Why the water kills, not the wind
Wind wrecks buildings, but people sheltering indoors usually survive it. Water is different: a surge of a few metres arrives within hours, fills ground-floor rooms and sweeps away whole houses. A study by the National Hurricane Center found that storm surge caused about half of all deaths from Atlantic hurricanes in the United States between 1963 and 2012 — more than wind, rain floods and tornadoes put together.
The great hurricane disasters were drownings. The 1970 Bhola cyclone drove a surge of up to 10 m over the islands of the Ganges delta and killed some 300,000 people. Cyclone Nargis in 2008 pushed about 4 m of seawater deep into Myanmar's flat Irrawaddy delta and killed 138,000. In the simulator you will see the same thing: in almost every run, the surge accounts for most of the toll.
Storms worth simulating
- Katrina over New Orleans — a category 3 with an 8.5 m surge
- Haiyan over Tacloban — the strongest landfall on record, 2013
- Bhola over Chittagong — the deadliest tropical cyclone ever recorded
- Sandy over New York — only a category 1, yet the subway flooded
- A category 5 over Miami — the scenario Florida plans for
- A super typhoon over Hong Kong — Mangkhut came within 100 km in 2018
What the model leaves out
This is a what-if built on real terrain and real population, not a forecast. The surge simply rises around the point you pick, the same on every side, while in a real storm it is highest to the right of the track in the northern hemisphere, where the wind blows onshore. Rain flooding, the tide, waves riding on top of the surge and the storm's path inland are not modelled, and neither are levees or sea walls: the elevation data only sees the ground.
And real hurricanes are forecast days in advance. Evacuation cuts the toll by orders of magnitude — Katrina killed about 1,800 people, not the hundreds of thousands the simulator shows for New Orleans with nobody leaving. The numbers here answer one question: how many people live where the water would go.
Questions
What is a storm surge?
A rise of the sea above the normal tide, caused mostly by the hurricane's wind piling water against the coast and a little by its low pressure lifting the sea surface. It is worst where the sea floor is shallow for a long way out, as in the Gulf of Mexico or the Bay of Bengal.
What is the difference between a hurricane, a typhoon and a cyclone?
Only the ocean. The same kind of storm is a hurricane in the Atlantic and the north-east Pacific, a typhoon in the north-west Pacific, and a cyclone in the Indian Ocean and the South Pacific. The simulator treats them all the same way.
Could a hurricane hit my city?
Hurricanes form over warm tropical seas and usually lose strength quickly over cold water and land, so they strike coasts between roughly 10° and 40° of latitude. The simulator lets you land one anywhere on a coast, which makes it a what-if for places like Europe that real hurricanes almost never reach.
Is the death toll realistic?
It is the toll if nobody evacuated, which makes it deliberately pessimistic. Storms without warning did kill on that scale — Galveston in 1900, Bhola in 1970 — but modern forecasts and evacuations usually keep deaths to a small fraction of it.