A powerful tropical cyclone in the northwest Pacific with sustained winds above 119 km/h. The same phenomenon is called a hurricane in the Atlantic and a cyclone in South Asia.
phenomenaWhat is a Typhoon?
A typhoon is a mature tropical cyclone in the northwest Pacific Ocean — west of the International Date Line and north of the equator — with sustained 10-minute winds of 119 km/h or more (33 m/s, or 64 knots).
The same storm system has different names depending on where it forms:
| Region | Name |
|---|---|
| Northwest Pacific | Typhoon |
| Atlantic, Northeast Pacific | Hurricane |
| North Indian Ocean (Bay of Bengal, Arabian Sea) | Tropical Cyclone or “Cyclonic Storm” |
| South Indian Ocean, South Pacific | Tropical Cyclone |
The word “typhoon” derives from the Chinese 颱風 (táifēng) or possibly the Arabic ṭūfān — both meaning “great wind.”
The northwest Pacific is the world’s most active tropical cyclone basin, averaging 26 named typhoons per year — more than any other ocean. The Philippines is the most typhoon-hit country on Earth, struck by an average of 20 named storms per year, of which 8–9 make landfall.
Why typhoons matter for South Asia
While South Asia’s tropical cyclones (Bay of Bengal, Arabian Sea) are formally separate from Pacific typhoons, the two basins are connected:
- The Madden-Julian Oscillation (MJO) modulates both Pacific typhoons and Indian Ocean cyclones simultaneously.
- El Niño/La Niña patterns affect both basins.
- Remnants of typhoons crossing the Indochina peninsula sometimes seed tropical disturbances in the Bay of Bengal.
- Northeast Indian states (Arunachal, Nagaland, Manipur, Mizoram) occasionally see heavy rain from Myanmar-crossing typhoon remnants.
Bangladesh and Myanmar also share weather systems with typhoon-affected regions — Cyclone Nargis (2008) is sometimes informally called a typhoon because of its Myanmar landfall.
Typhoon classification
Different agencies use different scales. The Japan Meteorological Agency (JMA) uses these categories:
| Category | 10-min wind |
|---|---|
| Tropical Depression | < 62 km/h |
| Tropical Storm | 62–88 km/h |
| Severe Tropical Storm | 89–117 km/h |
| Typhoon | 118–156 km/h |
| Very Strong Typhoon | 157–192 km/h |
| Violent Typhoon | ≥ 193 km/h |
The Joint Typhoon Warning Center (JTWC) uses the Saffir-Simpson scale (the same as Atlantic hurricanes), reaching Category 5 above 252 km/h. Names like “Super Typhoon” generally mean equivalent to Category 4 or 5.
Typhoon season
The northwest Pacific has typhoon activity all year, but the main season runs July to November:
- June–July: Activity ramps up; most typhoons over the central Philippines, South China Sea.
- August–September: Peak season; most landfalls.
- October–November: Late-season super typhoons; tend to be the most intense.
- December–February: Off-season activity over the Philippines and South China Sea.
Within this, landfall patterns depend on steering currents. Most typhoons move west or northwest into the Philippines, then either curve north toward Japan/Korea or continue west into Vietnam/China/Hainan.
Historic typhoons
Most deadly:
- 1881 Haiphong Typhoon, Vietnam: ~300,000 deaths (incredible death toll for a cyclone of any name).
- 2013 Typhoon Haiyan (Yolanda), Philippines: 6,300+ deaths; 315 km/h gusts at landfall.
- 1962 Super Typhoon Nora, Philippines: 8,000 deaths.
Most intense (recent):
- 2013 Haiyan: 895 hPa central pressure; world record for landfall intensity.
- 2020 Typhoon Goni, Philippines: 220 km/h at landfall — strongest landfalling typhoon on record.
- 2021 Typhoon Surigae: 895 hPa — extreme strength.
Most impactful internationally:
- 2018 Mangkhut: Devastated Philippines, then Hong Kong, then Macau.
- 2024 Typhoon Yagi: Vietnam’s deadliest typhoon in decades.
How typhoons form
The conditions required for typhoon genesis are the same as for any tropical cyclone:
- Warm sea surface temperatures ≥ 26.5°C in the upper 50 m.
- High humidity in the lower troposphere.
- Low vertical wind shear (under 10 m/s).
- Pre-existing disturbance (often an easterly wave).
- Far enough from the equator (typically 5°+ latitude) for Coriolis force.
- Atmospheric instability to support deep convection.
In the western Pacific, these conditions are satisfied for most of the year — which is why this basin produces more cyclones than any other.
Typhoon impacts
A major typhoon delivers multiple hazards:
- Sustained winds 120–250+ km/h flattening buildings, infrastructure.
- Storm surge 2–7+ metres in coastal flooding.
- Rainfall 300–1,500 mm during the event.
- Landslides in steep terrain (Philippines, Taiwan, Japan mountains).
- Tornadoes sometimes embedded in outer bands.
The Philippines and Vietnam are particularly vulnerable because:
- Densely populated coasts.
- Limited cyclone-resistant infrastructure.
- Mountainous terrain amplifying rainfall and flooding.
Early warning and evacuation
Joint Typhoon Warning Center (JTWC) in Pearl Harbor, USA, and Japan Meteorological Agency (JMA) issue twice-daily typhoon track forecasts up to 5 days ahead. National agencies (PAGASA in Philippines, VNCHMF in Vietnam, China Meteorological Administration) translate these into local warnings and evacuation orders.
Improvements over recent decades:
- Forecast track error at 72 hours has fallen from ~400 km in 1990 to under 200 km now.
- Mass evacuations before Haiyan (2013) saved hundreds of thousands; later events have done better.
- Modern building codes in Japan and Taiwan limit damage.
Frequently asked questions
What is the difference between a typhoon and a cyclone? They are the same type of storm — a mature tropical cyclone with sustained winds above 119 km/h. The name depends on where it forms: typhoon (western Pacific), hurricane (Atlantic, eastern Pacific), cyclone (Indian Ocean, southern Pacific).
Why does the Philippines get hit so often? The Philippines sits directly in the main typhoon “highway” — the southwest-to-northwest steering pattern of the northwest Pacific. The archipelago is densely populated with coastal cities, mountains and river deltas — high exposure to wind, surge and rain.
Can typhoons cross into the Bay of Bengal? Sometimes — typhoons crossing northern Vietnam and Laos can re-emerge as weakened systems over Myanmar or the Bay of Bengal. They occasionally reorganise into Bay of Bengal cyclones. This is one of several ways the western Pacific and Indian Ocean cyclone regimes interact.
Are typhoons getting stronger? Yes — research suggests the proportion of typhoons reaching Category 4 and 5 has increased over the past 40 years, while total numbers have not changed much. This is consistent with theoretical expectations of warming ocean surfaces fuelling more intense storms.
Where can I see typhoon-affected weather in my region? Mausam Online focuses on South Asia, but for Bay of Bengal and Arabian Sea cyclones (which share many drivers with Pacific typhoons), see Chennai, Visakhapatnam, Kolkata, Dhaka, Bhubaneswar.