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.
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.
Boun Pha Vet(January): This temple centered festival cerebrate the birth of Prince Vessanthara, the Buddha's penultimate existance. The jataka or birth story of Buddha is recited. This is the favored time for Lao men to become ordained as a monk. Festivities are staggered between villages so that different villages can visit one another to their celebrations.
Boun Ma Kha Bu Saar (February):This celebration commenorates a speech given by the Buddha in which he laid down the first monastic regulations and predicted his own death. The speech was heard by 1250 enlightened monks who arrived without prior summons. The festival is to celebrate with chanting and presenting offering carious Vat throughout the country. The biggest celebrations take place at the Khmer ruins of Vat Phu Champasack.
Boun Khoun Khao(March): Harvest festival are cerebrated in various villages throughout the month.
Boun Pi Mai/Laos New Year (April) : Pi Mai means "new year" and it is the time when the Lao cerebrates the start of their Lunar calendar year. Practically, the entry country grinds to a half for the festivities. Houses are cleaned, people wear new clothes and Buddha images are washed with holy water and this festival makes one of the best time to visit Laos.
Boun Visakha Bu Saar (May): Starting on the day of the sixth lunar month, this cerebration commemorates the birth, enlightenment and parinibbana (death) of Buddha. The festival is based and visitors can see chanting and sermonizing at night followed by beautiful candlelight processions.
Boun Bang Fai "Rocket Festival"(May-September): Various villages throughout the country take part in one that most boisterous festivals on the Lao calendar. This festival dated back to pre-Buddhist times and featuring home made rockets that are fired into the clouds to ask for rain as well as it amidst a great deal of raucous chanting and merry making.
Boun Ok Phansa and Boat Racing Festival (October):The festival held after the end of the monks’ three-month fast and retreat during the rainy season (Boun Khao Pansa). At dawn on the first day, donations and offerings are made at temples around the city. In the evening, candlelight processions are held at temples and hundreds of colorful floats decorated with flowers, incense and candles are set adrift down the Mekong River to pay respect to the river spirit. The following day in Vientiane, Savannakhet and Champasack Province, a popular and exciting boat racing competition is held to celebrate the Mekong River.
That Luang Festival and Trade Fair in Vientiane Capital (November):This religious festival is held in and around That Luang Stupa, the National Symbol of Laos, where hundreds of monks gather to accept alms and floral votives from the people. The festival includes a grand fireworks display at night. During the day, an international trade fair showcases tourism in Laos and other countries from ASEAN and the Greater Mekong Sub-region. During the same period a similar festival is also celebrated at Ching Tim Stupa in Luang Namtha Province.