Phuket's average temperatures don't vary that much due to its closeness to the equator. The weather is pleasantly warm all year round and it is a popular holiday destination for tourists coming from many parts of the globe. The island's weather is best described in three seasons: hot, wet and cold. The rainy season covers the months from May to October where more than 100mm will fall each month to the September high of 400mm. After the monsoon comes the cooler weather from November through to February and the hot season is March to May.
The hottest month here is March with an average temperature of 29°C between a low of 23°C and a high of 34°C. January is the coolest month with an average temperature of 27°C between a high of 32°C and a low of 22°C. The average temperature varies only 2 °C from 27°C to 29°C. The average high/low temperatures show little variation with a 3°C variation in the lows and a 4°C variation in the highs.
Rainfall varies due to the monsoon season and average rainfall varies from 30mm a month in February to 400mm in September. During the monsoon season, May to October, you can expect to see between 18 and up to 23 days of rain a month. Phuket is one of the earliest places to experience monsoon rains as they come in from the west. The most rain falls at the beginning of the season and the end of monsoon season where May, September and October will average 350mm to 400mm a month. The middle months average about 280mm each. Humidity will be higher during monsoon due to amount of moisture around and average humidity varies from 75% to a high of 90% in October.