December in Vientiane is the coldest month of the year. In December, the weather in Vientiane is typically warm. Average daily high temperature in December is about 25 degrees above zero. On average, Vientiane has 18 partly cloudy, 12 sunny, and 1 rainy day in December. The rains are usually light. December as well as January is considered the most comfortable time to visit Vientiane.