The typhoons that regularly lash Southeast Asia during monsoon season originate in the Pacific Ocean before moving west. With the addition of warm water, light winds, and humidity, a thunderstorm can grow in intensity to become a typhoon.
Not all tropical storms are typhoons. The word "typhoon" is the regional name for a particular kind of storm that hits the northwest Pacific Ocean. (That's pretty much all of Southeast Asia.)
As per the NOAA, a "typhoon" represents the extreme scale of the storm catalog; any storm worth calling a typhoon must have winds exceeding 33m/s (74mph).
In other parts of the world, storms with similar characteristics go by different names, namely hurricane in the Atlantic and Northeast Pacific and tropical cyclone along the Indian Ocean and South Pacific.
When Is Typhoon Season?
To speak of a typhoon "season" is somewhat inaccurate. While the majority of typhoons reliably develop between May and October, typhoons can occur any time of the year.
The Philippines' most damaging storm in recent memory, Typhoon Yolanda (Haiyan), made landfall in late 2013, causing over 6,300 deaths and an estimated $2.05 billion in damage.
What Countries Are Affected?
Some of Southeast Asia's most heavily-trafficked tourist destinations are also the most vulnerable to typhoon damage. Places close to the sea that possess fragile or underdeveloped infrastructure should throw up big red flags during typhoon season. These typhoon-induced occurrences can put a crimp on your travel plans:
- High winds: Winds in excess of 70kph can carry off roofs; even stronger winds can topple flimsy buildings and billboards. Flying objects can kill unsuspecting pedestrians.
- Storm surges: Typhoons are particularly dangerous in destinations close to the sea, as tidal surges often occur during such storms. These high tides can flood streets and destroy flimsy buildings (these surges are similar to, but completely distinct from, tsunami).
- Landslides: Typhoons bring driving rain, which can increase the risk of landslide in mountainous or hilly areas. If over 100mm of rain has fallen nonstop in a vulnerable area, it's time to consider evacuation.
- Restricted mobility: Airlines and bus routes can (and do) shut down in the event of a typhoon. After a typhoon passes, debris may block train tracks or roads, preventing you from getting from place to place.
- Natural devastation: Landslides, toppled buildings, overturned trees, and the like can mark the path of a typhoon. Death, too -- although satellite tracking and early warning systems do their part in clearing the typhoon path of potential victims, lowering the body count.
Not all countries in Southeast Asia are affected by typhoons. Countries with landmasses closest to the equator—Indonesia, Malaysia, and Singapore—possess a tropical equatorial climate that does not experience major climatic peaks and valleys.
Countries in the rest of Southeast Asia—the Philippines, Vietnam, Cambodia, Thailand, and Laos—are not as lucky. When typhoon season hits, these countries lie directly in harm's way. Luckily, these countries also closely track the progress of typhoons, so visitors usually get ample warning over radio, TV, and government meteorological sites.
The Philippines is generally the first stop for most typhoons, being the easternmost country in the typhoon belt.
The Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) is the government agency tasked to monitor and report the progress of tropical cyclones passing through its area of responsibility. Visitors to the Philippines can catch updates on the main TV channels or on their "Project Noah" website.
The Philippines follows its own naming system for typhoons, which may cause some confusion: Typhoon "Haiyan" in the rest of the world is known as typhoon "Yolanda" in the country.
Vietnam tracks the entry of typhoons into their territory via their National Centre for Hydro-Meteorological Forecasting, which runs this English language site to report typhoon progress.
Cambodia's Ministry of Water Resources and Meteorology runs the English-language Cambodia METEO site to update visitors on storms affecting the country.
What Should I Do in the Event of a Typhoon?
Southeast Asian countries affected by typhoons usually have a system in place for dealing with impending typhoons. When in such a country, follow any orders to evacuate without hesitation -- it may just save your life.
Watch out for warnings. Typhoons have a single saving grace: they're easily tracked by satellite. Typhoon warnings may be issued by government watchdog agencies between 24 to 48 hours before the typhoon is scheduled to make landfall.
Keep your ears open, as typhoon warnings will inevitably be broadcast on radio or TV. Asian feeds for CNN, BBC, and other news cable channels can provide up-to-date reports on impending typhoons.
Pack carefully. Bring clothes that can withstand the heavy winds and rains, like windbreakers, as well as plastic bags and other waterproof containers to keep important documents and clothes dry.
Stay indoors. It's dangerous to stay out in the open during a typhoon. Billboards can block the way or fall right on your vehicle. Objects sent flying by the high winds might injure or kill you outright, and electrical cables may fly free from overhead, electrocuting the unwary. Stay indoors in a safe area while the storm rages.
Make evacuation preparations. If your hotel, resort, or homestay isn't sturdy enough to withstand the typhoon, consider following the locals to a designated evacuation center.