News coverage treats a hurricane hitting the US and a typhoon approaching Korea as entirely different disasters, but they're actually the same phenomenon under different names. Here's why typhoons, hurricanes, and cyclones get called different things, plus the WMO's wind-speed classification.
Typhoons, hurricanes, and cyclones are all tropical cyclones that develop over warm tropical ocean water (26.5°C or higher), powered by heat released as water vapor condenses. Their structure is identical too — a clear "eye" at the center, a surrounding "eyewall" of intense wind and rain, and spiral rain bands — and there's no difference in how they form or operate.
Even though it's the same phenomenon, the name used depends on which ocean it forms over, following long-standing convention. One forming in the northwest Pacific (near Korea, Japan, the Philippines, China) is called a "typhoon"; one forming near North America and the North Atlantic is a "hurricane"; and one forming in the Indian Ocean, South Pacific, or Southern Hemisphere is a "cyclone." Internationally, meteorologists group all three under the term "tropical cyclone."
The World Meteorological Organization classifies tropical cyclones into four stages by maximum wind speed near the center.
| Stage | Max wind speed |
|---|---|
| Tropical depression | Under 17 m/s |
| Tropical storm | 17-24 m/s |
| Severe tropical storm | 25-32 m/s |
| Typhoon / hurricane / cyclone | 33 m/s or higher |
In other words, to be called a "typhoon," maximum wind speed must already exceed 33 m/s. Below that, it's a tropical depression or tropical storm, not a typhoon.
Once a storm becomes a hurricane, the North Atlantic and North American region additionally applies the separate 5-level Saffir-Simpson scale (Category 1-5) to break down expected damage by wind speed in more detail. That's the scale behind news reports of a "Category 4 hurricane." Typhoons don't use a separate numbered scale like this — instead, Korea's weather agency classifies intensity into its own tiers such as "medium," "strong," "very strong," and "super strong."
Typhoons draw from a rotating list of 140 names built jointly by 14 Asia-Pacific countries, while hurricanes draw from a separate annual, alphabetical list managed by a North Atlantic/North American committee. Both regions share the principle of permanently retiring the names of especially destructive storms. For more on how typhoon names are assigned, see Who Names Typhoons?
Since only the name differs while the mechanism is the same, you can understand hurricane and cyclone news from abroad the same way you'd understand typhoon news. Saving the places you check often in sanCheck lets you see advisory status and outdoor-activity score changes at a glance as a typhoon approaches Korea.