Laos- Climate and when to go to Laos

Climate
Laos has a monsoon climate of a dry and a wet season. The dry season lasts from November to May with the cooler period in December and January. At its coldest, the temperatures can fall to as low as 15 C. The cold periods tend to be at night and early morning with colder temperatures at higher altitudes.
During the hot period of the dry season, between March and May, temperatures can reach the high 30s.
 
The rainy season is a lot cooler, and rainfall varies according to altitude. Generally speaking, the monsoon season produces severe rain that lasts for short periods of time. The wet months vary according to location, in Vientiane, they are from May to September, in Luang Prabang, August is far wetter than any other month.
 
When to go
All year is fine. Please note that Laos is especially hot and humid (highs of 35 degrees plus) between March and June.

The winter months from October to February are generally the most pleasant. The country is at its greenest and most attractive during the wet season months from June to October or immediately afterwards. Smoke haze from traditional agricultural practices can dull the skies from March to May.