High season for tourism in Laos is November through March and the month of August, when weather conditions are favorable, plus the Lao New Year in the middle of April. Accommodations run at full capacity and transportation can be overbooked at these times.
Laos's tropical climate ushers in a wet monsoon season, lasting from early May to October, followed by a dry season from November through April. In Vientiane, average temperatures range from 71°F (22°C) in January to 84°F (29°C) in April. The northern regions get chilly from November to February and can approach freezing temperatures at night in mountainous areas. Beginning in mid-February, temperatures gradually climb, and April can see temperatures over 100°F (38°C). In order to avoid the rain and heat, November through February is the best time to visit southern Laos. In the mountains of the north, temperatures are still comfortable from May through July.
Laos festivals and events
The traditional Lao calendar is a solar-lunar mixed. The year itself is a rocketed by solar phases while the months are divided according to lunar phases. The Lao Buddhist Era (BE) calendar started in 638 BC.
Festivals in Laos are largely linked to agricultural seasons or historical Buddhist holidays and the general word for festival in Lao is "BOUN." In general lao people like to party and they enjoy festivals as long as possible. Some of the festivals - like the new year - inofficially start a few days earlier and go on for about a week. If you want to have fun instead of sightseeing you should choose the Pi Mai festival...