Typhoon
A tropical cyclone with sustained winds of 74 mph or greater in the Western Pacific. Typhoons are meteorologically identical to hurricanes; the different name reflects only their geographic location.
More Tropical Weather Terms
Hurricane
A tropical cyclone with maximum one-minute sustained surface winds of 74 mph or greater in the Atlantic or eastern and central North Pacific. Hurricanes are categorized 1-5 on the Saffir-Simpson Hurricane Wind Scale, with Category 5 beginning at 157 mph.
Cyclone
A rotating low-pressure weather system. Tropical cyclone terminology and intensity categories vary by region: in Australia, a tropical cyclone has maximum sustained winds of at least 34 knots (63 km/h, about 39 mph), averaged over ten minutes. The term does not universally require hurricane-force winds of 74 mph.
Eye Wall
The ring of intense thunderstorms surrounding a hurricane's eye, containing the storm's strongest winds and heaviest rainfall. Eye wall replacement cycles can temporarily weaken a hurricane before it potentially re-intensifies.
Storm Surge
Storm surge is an abnormal rise in sea level during a hurricane or other intense storm, measured as the height of the water above the normal predicted tide. It is produced mainly by the storm's winds pushing water toward the shore. Storm surge is the leading cause of deaths from hurricanes.
Tropical Depression
An organized system of clouds and thunderstorms with defined circulation and maximum sustained winds of 38 mph or less. Tropical depressions can strengthen into tropical storms and eventually hurricanes.
Tropical Storm
A tropical cyclone with maximum sustained winds between 39-73 mph. At this stage, the storm receives a name. Tropical storms can produce dangerous flooding, winds, and tornadoes even without reaching hurricane strength.
Invest
A weather system designated for investigation by the National Hurricane Center. An Invest designation triggers enhanced data collection and model runs but does not indicate expected development. Many Invests never become tropical cyclones.
Saffir-Simpson Scale
The Saffir-Simpson Hurricane Wind Scale rates hurricanes from Category 1 to Category 5 by maximum sustained wind speed. Category 1 starts at 74 mph and Category 5 at 157 mph, and Category 3 and higher are called major hurricanes. The scale measures wind only: it does not account for storm surge, rainfall flooding, or tornadoes.
Post-Tropical Cyclone
A post-tropical cyclone is a former tropical cyclone that no longer has enough tropical characteristics to be classified as one. It can still bring heavy rain and strong winds. The two kinds are extratropical cyclones, which draw their energy from temperature contrasts between air masses, and remnant lows, which have winds below 34 knots (39 mph).
Typhoon: Guides and Explainers
These explainers connect this definition to real-world forecasting and decision-making.
Weather Education
Typhoon vs Hurricane vs Cyclone: Same Storm, Three Names
A typhoon and a hurricane are the same kind of storm with the same 74 mph threshold. What changes is the ocean basin, the agency, and how the wind is measured. Here is the full naming map.
Weather Education
What Is an Invest in Weather? What 90L, 91L, and 92L Actually Mean
An Invest is a data-collection label, not a forecast. Here is what the National Hurricane Center means by Invest 90L, how the numbering and basin codes work, and how an Invest becomes a named storm.
Weather Education
What Is Storm Surge? Surge vs Storm Tide, and Why Category Doesn't Predict It
Storm surge explained: how surge, storm tide, and inundation differ, what decides how high the water gets, why a Category 2 can flood worse than a Category 4, and which NHC products to act on.
Helpful Tools and Hubs
Use these pages to apply the concept, compare conditions, or follow related weather workflows.
Live Tracker
Live Hurricane Tracker
Follow every active Atlantic and Pacific storm with the official NHC cone of uncertainty and forecast track, refreshed continuously.
Guide
Hurricane Categories Explained
Understand what each Saffir-Simpson category says and what it does not say about a storm's risk.
Seasonal Hub
Hurricane Season Guide
Track tropical risk, categories, and preparedness advice in one place.
Feature
Hurricane Tracker
Track cones, watches, warnings, and tropical systems from formation through landfall.
Explore Other Terms
Tornado
A tornado is a violently rotating column of air in contact with the ground, extending from a thunderstorm. Tornadoes are rated from EF0 to EF5 on the Enhanced Fujita scale by the damage they cause. Most last less than 10 minutes, but the strongest can stay on the ground for more than an hour.
Graupel
Soft, small pellets of ice formed when supercooled water droplets freeze onto falling snowflakes. Also called snow pellets, graupel is crumbly and opaque, unlike the hard, clear ice of hail. It often occurs in spring and fall storms.
Wind Shear
A change in wind speed or direction over a short distance, either horizontally or vertically. Strong wind shear is essential for supercell and tornado development but is also a significant hazard to aircraft during takeoff and landing.
Velocity
Doppler radar measurement of how fast precipitation is moving toward or away from the radar. Velocity data reveals wind patterns, rotation in thunderstorms, and potential tornado signatures that reflectivity alone cannot show.
Ensemble Forecast
A collection of multiple model runs with slightly different initial conditions, showing the range of possible outcomes. Ensemble forecasts help quantify uncertainty and are especially valuable for medium-range predictions.
VFR
Visual Flight Rules allow flight using visual references when the applicable visibility and cloud-clearance minimums are met. Those minimums vary by airspace class, altitude, and day or night under 14 CFR 91.155. Separately, the VFR weather category means a ceiling above 3,000 feet and visibility greater than 5 statute miles.
Browse by Category
Get the WeatherAI App
WeatherAI is a weather app for iPhone, iPad, Mac, Apple Watch, and Apple Vision Pro. It is free to download.