What Is a Typhoon? Definition, Season & Preparedness

What Is a Typhoon?

A typhoon is a tropical cyclone that forms in the Northwest Pacific Ocean, west of the International Date Line. Typhoons are structurally and meteorologically identical to Atlantic hurricanes and Indian Ocean cyclones — they are the same type of storm. The only difference is geography: where the storm forms determines what it is called.

Typhoon — Northwest Pacific Ocean (west of the Date Line)
Hurricane — Atlantic Ocean or Northeast Pacific Ocean
Cyclone — Indian Ocean or South Pacific Ocean

Same formation mechanics. Same spiral structure. Same destructive potential. Different basin, different name.

This is not a minor distinction worth ignoring. The Northwest Pacific is the most active tropical cyclone basin on Earth. It produces more storms, stronger storms, and larger storms than any other ocean basin. Typhoon Tip (1979) remains the largest and most intense tropical cyclone ever recorded anywhere on the planet.

Typhoon vs. Hurricane: Is There Any Real Difference?

Beyond the name, the differences are minor and regional — not meteorological.

Wind speed thresholds differ slightly. In the Atlantic basin, the National Hurricane Center (NHC) classifies a storm as a hurricane once sustained winds reach 74 mph (64 knots). In the Northwest Pacific, the Japan Meteorological Agency (JMA) uses 64 knots (about 74 mph) as the typhoon threshold — essentially identical. The Joint Typhoon Warning Center (JTWC), operated by the US military, uses the same 64-knot threshold.

The “super typhoon” classification has no Atlantic equivalent. The JTWC designates a storm a “super typhoon” when it reaches 130 knots (approximately 150 mph) — roughly equivalent to a strong Category 4 or Category 5 on the Saffir-Simpson scale. The Atlantic basin has no official equivalent term.

Rotation direction is the same. Both typhoons and hurricanes rotate counterclockwise in the Northern Hemisphere due to the Coriolis effect.

Scale tends to be larger. Northwest Pacific typhoons are, on average, physically larger than Atlantic hurricanes. Typhoon Tip’s diameter reached approximately 1,380 miles at its peak — roughly the distance from New York City to Denver.

For practical preparedness, treat typhoons and hurricanes as the same threat. The survival priorities — shelter, supplies, evacuation decision, post-storm hazards — are identical.

How Do Typhoons Form?

Typhoon formation follows the same process as any tropical cyclone. Three conditions must align:

1. Warm ocean water. The ocean surface must be at least 79 degrees Fahrenheit (26 degrees Celsius) to a depth of roughly 150 feet. Warm water provides the thermal energy that drives the storm’s convection. The Northwest Pacific maintains warm surface water across a vast area from June through November, which is why typhoon season peaks during those months.

2. Low atmospheric wind shear. Wind shear — the difference in wind speed and direction at different altitudes — can tear a developing storm apart before it organizes. Low wind shear allows the storm’s vertical structure to build upward, forming the characteristic tall thunderstorm towers of the eyewall.

3. An initial disturbance. Most Northwest Pacific typhoons develop from tropical disturbances originating in the monsoon trough — a region of persistent low pressure that stretches across the tropical Pacific during summer. These disturbances are clusters of thunderstorms with a weak rotation that, given the right conditions, can organize into a typhoon.

Once these conditions align, the process accelerates:

Warm ocean water heats the air above it, which rises and creates a low-pressure center at the surface.
Surrounding air rushes in to replace the rising air, is heated in turn, and rises — creating a cycle of convection.
The Coriolis effect imparts a spin to the inflow — counterclockwise in the Northern Hemisphere.
The system develops a defined eye (the clear, calm center) surrounded by the eyewall — a ring of intense thunderstorms with the strongest winds and heaviest rain.
Spiral rainbands extend outward from the eyewall, capable of producing tornadoes and flooding rain far from the storm’s center.

Rapid intensification — when a typhoon’s winds increase by 35 mph or more in 24 hours — is a particular hazard. Typhoon Haiyan (2013) underwent rapid intensification in the 24 hours before landfall, going from a strong typhoon to the most powerful landfalling storm on record.

Typhoon Categories: The Saffir-Simpson Equivalent

There is no separate “typhoon category scale.” The Saffir-Simpson Hurricane Wind Scale (SSHWS) — the Category 1 through 5 scale familiar to anyone who has followed Atlantic hurricane news — applies equally to typhoons when comparing storm intensity. Emergency managers and the US military use Saffir-Simpson for cross-basin comparisons.

Saffir-Simpson Category	Sustained Wind Speed	Typhoon Designation (JTWC)
Category 1	74 to 95 mph	Typhoon
Category 2	96 to 110 mph	Typhoon
Category 3	111 to 129 mph	Typhoon
Category 4	130 to 156 mph	Super Typhoon
Category 5	157 mph or higher	Super Typhoon

The Japan Meteorological Agency uses its own intensity scale with different wind thresholds and terminology (Tropical Storm, Severe Tropical Storm, Typhoon, Very Strong Typhoon, Violent Typhoon). For international or US preparedness purposes, Saffir-Simpson equivalents are the most practical reference.

Key point for preparedness: A super typhoon is approximately equivalent to a Category 4 or 5 hurricane. The storm surge and flooding hazards are equivalent as well — surge is often the primary killer regardless of which ocean basin the storm forms in.

Notable Typhoons: The Strongest Ever Recorded

Typhoon Haiyan (2013) — Strongest Landfalling Typhoon Ever

Typhoon Haiyan — called Typhoon Yolanda in the Philippines — struck the Visayas region of the Philippines on November 8, 2013. Its maximum sustained winds at landfall were approximately 195 mph, with gusts estimated as high as 235 mph. It is the strongest tropical cyclone at landfall ever recorded anywhere on Earth.

Haiyan’s storm surge reached as high as 20 feet in Tacloban City, the regional capital, moving miles inland and overwhelming areas that residents had assumed were safely elevated. The surge — not the wind — was responsible for the majority of the approximately 6,300 confirmed deaths.

The aftermath exposed a critical preparedness failure: residents who evacuated to evacuation centers at ground level died from the surge. Effective typhoon preparedness in low-lying coastal areas requires vertical elevation, not just horizontal distance from shore.

Typhoon Tip (1979) — Largest and Most Intense Ever Recorded

Typhoon Tip reached its peak intensity on October 12, 1979, with a central pressure of 870 millibars — the lowest atmospheric pressure ever recorded in any tropical cyclone on Earth. Its maximum sustained winds reached approximately 190 mph. Its diameter at tropical storm strength spanned roughly 1,380 miles.

Tip weakened significantly before making landfall in Japan and caused 99 deaths — far fewer than Haiyan — largely because it struck a well-prepared nation at reduced intensity. The comparison between Tip and Haiyan illustrates the role of preparedness: storm intensity matters, but community readiness and evacuation compliance often determine the final death toll.

Other Notable Typhoons

Typhoon Vera (Isewan Typhoon, 1959): Struck Japan with a storm surge that killed approximately 5,000 people. Japan’s comprehensive coastal flood defense infrastructure was built largely in response to this storm.
Typhoon Bopha (2012): Made landfall in Mindanao, Philippines — an area not historically in the main typhoon track — killing over 1,900 people. A reminder that typhoon tracks can shift into regions with lower preparedness infrastructure.
Typhoon Hagibis (2019): A Category 5-equivalent storm that struck Japan with massive rainfall, triggering over 140 river flood events and killing 98 people. Rainfall flooding killed more people than the wind.

Typhoon Season: When and Where

Official typhoon season: June 1 through November 30 in the Northwest Pacific, mirroring the Atlantic hurricane season calendar. Peak activity occurs in August, September, and October — with September being statistically the most active month.

The key distinction from other basins: The Northwest Pacific can produce typhoons at any time of year. Off-season typhoons are uncommon but not rare. In 2021, Typhoon Rai (Odette) struck the Philippines in December — well outside the peak season — and killed over 400 people.

Most affected countries and territories:

Philippines: Approximately 20 typhoons enter the Philippine Area of Responsibility every year, with 8 to 9 making landfall. The Philippines bears a disproportionate share of typhoon casualties globally.
Japan: Receives an average of 11 named storms per year in its vicinity, with 3 to 4 making landfall. Japan’s infrastructure and warning systems are among the best in the world.
China: Southern China, particularly Guangdong province, is regularly struck by typhoons that weaken after crossing the Philippines.
Taiwan: In the direct path of many Northwest Pacific typhoons tracking north from the tropics.
Vietnam: Receives 6 to 8 typhoons per year on average, often striking after the storms have crossed the Philippines and weakened.
US Territories: Guam and the Northern Mariana Islands lie in one of the most active typhoon corridors on Earth. Super Typhoon Pongsona (2002) and Typhoon Mawar (2023) both caused severe damage to Guam.

Geographic note for US residents: If you are stationed at or visiting Andersen Air Force Base or Naval Base Guam, or living on any of the Northern Mariana Islands, you are in a typhoon zone. The same preparedness principles that apply to Gulf Coast hurricane residents apply to you — with potentially stronger storms and less external support immediately after a strike.

Typhoon Preparedness: What to Do If You Are in a Typhoon-Prone Region

The preparedness framework for typhoons is identical to hurricane preparedness. The hazards are the same — storm surge, wind damage, flooding rain, tornadoes in outer bands, infrastructure collapse, prolonged power outages — and the response is the same.

Know Your Surge Zone, Not Just the Category

Typhoon Haiyan’s storm surge killed thousands in areas that residents and some officials believed were safe based on the elevation relative to sea level. Storm surge is driven by storm intensity, track angle, approach speed, and local topography — including how your coastline funnels water.

In the Philippines, PAGASA (the Philippine Atmospheric, Geophysical and Astronomical Services Administration) publishes storm surge inundation maps for high-risk coastal areas. In Japan, the Japan Meteorological Agency and local governments maintain detailed surge risk maps. In Guam and the CNMI, the National Weather Service provides inundation guidance.

Know your specific surge inundation zone before typhoon season starts — not when a storm is 48 hours from landfall.

Evacuation: Go Early

Evacuation compliance is lower in typhoon-affected regions than it should be, often because residents have survived previous storms in place and underestimate the surge risk. The historical record is clear: the most effective predictor of low casualty rates is early evacuation of surge-risk zones.

If local authorities issue an evacuation order for your zone, leave. If you are in a low-lying coastal area with a super typhoon approaching, leave without waiting for an order.

Vertical evacuation (moving to upper floors of a reinforced concrete building) is only appropriate when horizontal evacuation is impossible due to time constraints. Ground floors in surge zones offer no protection.

Build a 14-Day Supply Buffer

Post-typhoon infrastructure recovery in affected regions can take weeks to months. After major typhoons in the Philippines, Japan, and Taiwan, disruptions to water, power, and supply chains commonly last one to four weeks even in areas not directly on the storm’s path. In rural or island communities, recovery can take far longer.

Minimum preparedness supply targets:

Water: 1 gallon per person per day for 14 days minimum, stored in sealed containers
Food: Two weeks of shelf-stable, no-cook or minimal-cook meals per person
Medications: 30-day supply of any essential prescriptions, stored in waterproof containers
Power: Battery banks for communication devices; a portable power station (1,000 Wh or more) for essential devices if budget allows
NOAA/local weather radio: In US territories, a battery-powered weather radio is essential for official alerts when cell service is disrupted

Structural Preparation Before the Storm

Bring all outdoor items — furniture, potted plants, signs, equipment — inside or securely anchor them. Wind-borne debris kills and destroys.
Board windows or install storm shutters if you are sheltering in place.
Know the strongest interior room in your structure (interior rooms on upper floors of concrete buildings for wind; upper floors for surge).
Identify the nearest official evacuation shelter with surge-safe elevation and know the route on foot, not just by vehicle.

After the Storm: The Hidden Dangers

Typhoon aftermath hazards mirror those of hurricanes precisely:

Multiple waves / continued surge: Do not return to the coast after the first surge wave. Tidal cycles and storm residue can produce dangerous water conditions for 12 to 24 hours after the main eyewall passes.
Contaminated floodwater: Post-typhoon floodwater contains sewage, chemicals, debris, and biological hazards. Treat all floodwater as contaminated.
Structural integrity: Typhoon winds and water can compromise buildings that appear intact from the outside. Do not enter damaged structures without assessment.
Downed power lines: Assume any downed line is live. Stay away and report.

For a full preparedness supply framework, see our emergency preparedness checklist. For a deep dive into the Saffir-Simpson scale and how category numbers translate to real-world damage, see our guide to hurricane categories and the Saffir-Simpson scale.

The Bottom Line

A typhoon is a hurricane. A hurricane is a typhoon. They are the same storm wearing different names based on which ocean they form in.

The Northwest Pacific — where typhoons form — is the most active tropical cyclone basin on the planet, producing storms that are on average larger and sometimes more intense than their Atlantic counterparts. Typhoon Haiyan demonstrated what a direct super typhoon strike looks like at its worst: 195 mph winds, 20-foot storm surge, and over 6,000 deaths in a single landfalling event.

If you live in, work in, or travel to typhoon-affected regions — the Philippines, Japan, Taiwan, Vietnam, Guam, the Northern Mariana Islands — the preparedness actions are identical to what Gulf Coast and Eastern Seaboard residents do for hurricanes. Know your surge zone. Build your supplies. Leave early.

The name on the forecast map changes by ocean basin. The storm does not.

For broader natural hazard context, see our natural disaster preparedness guide.

Sources: Joint Typhoon Warning Center (JTWC) best-track data; Japan Meteorological Agency tropical cyclone records; PAGASA official records; National Oceanic and Atmospheric Administration (NOAA) tropical cyclone climatology; World Meteorological Organization tropical cyclone program; NOAA National Hurricane Center Saffir-Simpson Hurricane Wind Scale documentation; peer-reviewed analyses of Typhoon Haiyan (2013) storm surge, published in Nature Geoscience and Natural Hazards; Japan Meteorological Agency post-storm reports for Typhoons Vera (1959), Tip (1979), and Hagibis (2019).

Frequently Asked Questions

What is the difference between a typhoon and a hurricane?

There is no meteorological difference. Both are tropical cyclones — the same type of storm with the same formation mechanics, structure, and destructive potential. The name depends entirely on where the storm forms. Typhoon = Northwest Pacific Ocean. Hurricane = Atlantic Ocean or Northeast Pacific. Cyclone = Indian Ocean or South Pacific. Same storm, different basin, different name.

What is a super typhoon?

A super typhoon is a typhoon with maximum sustained winds of at least 130 knots (approximately 150 mph). It is roughly equivalent to a Category 4 or 5 hurricane on the Saffir-Simpson scale. The term is used by the Joint Typhoon Warning Center (JTWC), the US military's tropical cyclone tracking agency. It has no direct equivalent classification in the Atlantic hurricane naming system.

When is typhoon season?

Typhoon season in the Northwest Pacific officially runs June through November, with peak activity in August, September, and October. However, typhoons can form at any time of year in the Northwest Pacific — the basin is the most active tropical cyclone basin on Earth, capable of producing storms year-round. The Philippines, Japan, China, Vietnam, and Taiwan are the most frequently affected countries.

What was the strongest typhoon ever recorded?

Typhoon Haiyan (known as Yolanda in the Philippines) made landfall on November 8, 2013, with sustained winds of approximately 195 mph — the strongest tropical cyclone at landfall ever recorded. It struck the Philippines with a catastrophic storm surge and killed an estimated 6,300 people, with over 1,000 still listed as missing. Typhoon Tip (1979) holds the record for the largest and most intense tropical cyclone ever recorded anywhere on Earth by central pressure.

Do typhoons affect the United States?

Yes. Guam, the Commonwealth of the Northern Mariana Islands (CNMI), and the US territory of the Northern Marianas are directly in the Northwest Pacific typhoon belt and have been struck multiple times. Additionally, the western Pacific coast of the Philippines, Japan, and Taiwan — all close US treaty allies — are regularly devastated by typhoons. Typhoons occasionally affect Hawaii and the US West Coast indirectly through remnant moisture and wave action.

How do typhoons form?

Typhoons form when warm ocean water (at least 79 degrees Fahrenheit, or 26 degrees Celsius) heats the air above it, causing it to rise. Surrounding air rushes in to replace it, is heated and rises in turn, and the cycle creates a low-pressure center. Earth's rotation (the Coriolis effect) causes the inflow to spiral — counterclockwise in the Northern Hemisphere. If conditions are favorable — warm water, low wind shear, sufficient moisture — the system organizes into a tropical depression, then a tropical storm, then a typhoon.