Laos has a tropical climate with two distinct monsoon seasons. The wet southwest monsoon season runs from May to October while the northeast monsoon in the months of November to April brings drier weather. Though most of the country has warm temperatures year-round, it can get down to freezing conditions in the mountainous areas.
From the end of January to May the temperatures rise and it can get very sticky when the rains arrive in May. Daytime temperatures over 35°C are not unusual during these months. From June to October expect a fair bit of rain, even flooding in the Mekong River area. This region is also the country's warmest, with temperatures ranging from 15°C to the mid-30s. The higher altitude areas including Vientiane have more rainfall than the lowlands.
The best time to visit Laos is from November to February with the coolest, driest days as well as some of the country's most colourful festivals to enjoy.