March in Koh Lanta Yai is the hottest month of the year. In March, the weather in Koh Lanta Yai is typically hot. Average daily high temperature in March is about 29 degrees above zero. On average, Koh Lanta Yai has 11 rainy, 11 sunny, 7 partly cloudy, and 2 cloudy days in March. The rains are usually heavy.