Surprisingly, Vietnam’s weather is not particularly extreme, apart from torrential rain in areas that experience summer or autumn monsoons, drought conditions in some places and, occasionally, typhoons.

Typhoons
‘Typhoon’ is the name used in the west Pacific/China Sea region for tropical cyclones. They are small, but very intense, low-pressure areas that produce violent winds and torrential rain. The tropical cyclones that affect Vietnam form over the ocean in a band stretching from the equator to latitude 50 north, and then moves slowly northward following a well-defined clockwise course at around 20km per hour. A fully developed cyclone has a diameter ranging between 150km to 300km, and is one of the most destructive forces in nature.

Vietnam is well to the north of the tropics, so the power of typhoons is weakened by the time they reach its coast. Even so, a typhoon will usually have retained enough energy to devastate crops and buildings, and sometimes cause loss of life among people living in coastal areas. Fortunately, its slow approach gives plenty of time to rearrange itineraries if necessary.

Tropical storms
Tropical storms are frequent in the summer. Typically, they are preceded by a darkening of the sky, a drop in temperature and a fresh wind. Shortly after, the storm heralds its arrival by lightning and a colossal clap of thunder. The noise and flashes continue for a while, and rain begins to fall, slowly at first, then a deluge. After an hour or two, the rain stops, the skies clear and the temperature and humidity rise rapidly. Tropical storms tend to occur more commonly in afternoons or at night.

As far as visitors are concerned, weather agencies will be aware of the approach of a typhoon several days in advance – plenty of time for schedules to be re-routed to avoid any risk. Tropical storms are spectacular and noisy, but do little more than give visitors a soaking if they are unlucky enough to be caught without shelter. Of course, warnings about not standing under tall trees, playing golf, etc. in thunderstorms apply to tropical storms as well!

There are occasional heavy hailstorms in the Central Area. Hailstones can reach the size of golf balls and are obviously dangerous, but occur very infrequently. Damage is usually confined to crops, roof tiles, glass and vehicles.

The Central Highlands
The Central Highland plateau and other central and southern areas are prone to prolonged heat waves causing drought and salination of lakes and rivers in the early months of the year. Although posing considerable problems for farmers, visitors are not affected.

Flooding
Heavy flooding lasts about three months occurs in the Mekong Delta from August onwards. This is seldom a problem for visitors as itineraries can usually be rerouted to avoid problems. Indeed, experiencing the Mekong in flood reveals the remarkable ways in which the inhabitants of the region cope with an annual inundation of several metres of water.

Flooding can also occur elsewhere in the country, particularly in the Hue area and on the Red River delta. The main implication for visitors is the need to revise itineraries and/or switch from road or rail to air travel if flooding is severe enough to affect land routes.

In the northern mountains, heavy rain can result in flash floods capable of washing away bridges, animals and people. With that in mind, we only use highly experienced local guides that can anticipate, and thus avoid, any risk. During the rainy season, we suspend climbing and ‘hard’ trekking altogether as rock surfaces become slippery and heavy mud causes problems.