The tropical climate and weather on Koh Phangan bring warm and humid conditions all year round. The average temperature measured over 12 months is approximately 30 degrees Celsius and water temperature is a steady 28 to 29 degrees Celsius.
Like the rest of Thailand, the weather here is influenced by the monsoons and the island experiences its driest season from December to February with very little if any rain. The average maximum temperature during this time vary between 30 and 32 degrees Celsius and the minimum average 23 degrees Celsius.
March to August is a good time to visit Koh Phangan if you enjoy higher temperatures. You can expect maximum temperatures of 30 to 35 degrees during this time and minimum temperatures in the evenings of between 27 and 32 degrees. You may experience a little rain during May and even some during June and July. Usually these are short bursts of rain followed by sunshine.
September through November sees regular showers which seldom last more than an hour. Temperatures are still warm and lots of sunshine are to be enjoyed. Maximum temperatures during this time average 31 degrees Celsius and minimum temperatures 24 degrees. This is low tourism season sees lower resort prices. On average, 250 mm of rain per month fall during this time with November seeing up to 300 mm.