January in Koh Lanta Yai is the windiest month of the year. In January, the weather in Koh Lanta Yai is typically hot. Average daily high temperature in January is about 29 degrees above zero. On average, Koh Lanta Yai has 12 rainy, 8 partly cloudy, 7 cloudy, and 4 sunny days in January. The rains are usually heavy.