Laos Weather

Laos' wet season runs from around May to October, and as with many Southeast Asian countries, the wet season is characterised by a downpour for a few hours a day rather than all day torrential rain. While the rainy season tends to strike Laos pretty much uniformally there are a couple of regional oddities. Laos' wet season tends to hit Phongsali a little early due to it catching a bit of rain from southern China, while Hua Phan and Xieng Khuang tend to get a little early rain from Vietnam. Generally speaking, the higher you are the more rain you get, and the towns along the Mekong River south of Vientiane get the least rain.

As with Cambodia, the most obvious effect of the wet season is damaged infrastructure. Landslides remain common, as do severly rutted roads. While the road network is generally far better (ie., sealed) than in Cambodia, the topography of Laos (pretty mountainous) lends itself to landslides -- some minor, some not-so-minor. Also, with all this rainfall, the rivers can become pretty beastly and delays due to bridges being down are not uncommon. Don't be surprised if your trip takes longer than expected.

All in all, land transport during Laos' wet season can be slow and soggy.

On the upside, it is during wet season that boat transport comes into its own. The rivers are high so the slow boats can make better pace. Along the Mekong River many of the rapids are submerged -- helping the slowboats with their deeper drafts, but if you're considering a speedboat trip, be warned the heavy rainfall brings a lot of refuse into the river, and hitting a submerged log at 50km/h can be very messy -- yet another reason not to go with the speedboats.

Other advantages include lower temperatues, cleaner air and smaller crowds.

Laos' dry season has two distinct sub-sections -- first comes the cool dry season and then comes the hot dry season -- the former is one of the most popular times to visit Laos, the later less so. The cool dry season runs from November to February and the hot dry season from March to April. What the hot season lacks in length it makes up in ferocity -- they don't call it the hot season for nothing.

What makes the hot season even more unbearable is the smoke factor -- from March to May farmers set fire to rice stubble and degraded (and not-so-degraded) forest to improve soil fertility in preparation for a new rice crop. The resulting fires bathe most of Laos (including Luang Prabang) in a layer of smoke which, aside from ruining vistas and photos can become really irritating to the eyes. March to May in Laos -- yuck!

The cool dry season on the other hand is an excellent time to go. Temperatures are relatively low, the air is cleaner and, particularly in November and December, the rivers are high enough to make river travel a breeze. Not surprisingly, this period in Laos is the peak season.

Temperature and rainy days statistics for Vientiane, Laos

The temperature tends to be a few degrees cooler in Luang Prabang and northern Laos than in Vientiane -- in Phonsavan and Phongsali in particulr temperatures can drop to the low teens or even single digits (in centigrade - not fahrenheit!)

Summary

Dry season runs from November to April. November to February are cooler while March and April are blisteringly hot. April is the hottest month.

Wet season runs from May to October, though it may start a little early in a couple of Laos' northern provinces. August is the wettest month.