The best time to visit Luang Prabang is between November and March when it is dry and not too hot. However, December and January are peak months, when hotel costs are at their maximum, and the city is quite crowded. The same is true for the Chinese New Year in February.
From March through May, Luang Prabang experiences dry weather but also the warmest months of the year, with daytime highs of approximately 95°F (35°C) and nightly lows of around 71°F (22°C). The rainy season in Luang Prabang lasts from May until October, when the Monsoon arrives. While there may be some rain, hotel costs will be lower, and there will be fewer customers if you visit Luang Prabang during the low season months.
Luang Prabang is one of the most touristy places in Laos, so it's no problem to find a nice tourist spot to visit. Do not forget to apply for a Laos visa before traveling to this country.