The weather in Koh Phangan is generally excellent. That is one of the main reasons why the island is such a popular holiday destination. Nearly all year round you are guaranteed hot and sunny weather, and depending on the beach, you can be guaranteed year round swimming in the sea.
It must be remembered that Koh Phangan has its own micro climate governed by winds in the gulf, pressure zones, the mountainous terrain etc. The island is still 90% covered with virgin forest. It is often called ‘rainforest’. I’m not sure this is an accurate description – in the Amazon it rains nearly every day. That is not the case in Koh Phangan. Rather you will notice that after a few really hot days the humidity will raise dramatically and then there will be a quick downpour of rain followed by blue skies and lower humidity.
The wet season or monsoon in Thailand starts in the north and moves south. The timing of the monsoon varies by a few days every year. In Koh Phangan the monsoon usually hits at the end of October or the start of November. It rains heavily for about a month and then eases off. During the height of the rainy season the waves really pick up. It is not advised that you swim during the monsoon. The waves are not for surfing. They are dangerous and have a strong undertow on many of the beaches. Indeed, it is unlikely that you will stay in Koh Phangan during monsoon. Several businesses shut up during this period and many of the beaches become cut off because of flooded roads. Many of the ex-pats go up north to places to Chiang Mai during the rainy season in Koh Phangan to dodge the bad weather. Expect serious disruption to ferry and other transport links during October and November.
The peak season in Koh Phangan and elsewhere in Thailand is the Christmas and New Year period. Party organizers ignore the course of the moon and throw Christmas and New Year ‘Full Moon’ Parties that are the busiest of the year. The weather at this time is hit-and-miss. Many of the beaches will still have sand bags from the monsoon. The skies are often grey and there is the occasional downpour.
From the graphic above you can see the average rainfall and temperature for each month of the year. This naturally changes slightly from year to year. In 2011 it changed considerably – there were heavy rains in March (that flooded Bangkok and other parts of Thailand causing landslides, property damage and loss of life) and a fairly gentle monsoon. This pattern did not repeat itself in 2012 gratefully.
The hottest months in Koh Phangan are March and April. Temperatures are on average 32 degrees but can climb to 36 degrees. The other months have an average temperature of 30 or 31 degrees. These figures are slightly deceptive – June and July feel hotter and more humid than October to December.
In terms of rainfall, January and February are the driest months and October and November are the wettest months. From May to August there is a pattern of hot weather followed by sudden rainstorms.
March to November is the low tidal season. On beaches like Srithanu, Wok Tum, Hin Kong, Nai Wok and Haad Khom swimming is confined to the part of the day when the tide is high. These beaches are better during the high tidal period from December to April. Beaches in the north and East such as Bottle Beach, Chaloklum, Thong Nai Pan Noi and Yai, Than Sadet, Haad Thian and Haad Yuan have little tidal difference throughout the year – they don’t have a coral reef and are thus great for year round swimming but not snorkeling.
I personally love June the best in Koh Phangan. The sky is bright blue. The sea is flat and warm like a bath and the beaches in the afternoon are virtually empty. The summer holiday crowds haven’t arrived yet and it is often just me and a couple of dogs sitting in the shallows cooling off. I believe that June also has the best light for taking photographs. In contrast, December is the most expensive month to stay on the island and has some of the most average weather. It just goes to show how out-of-synch holidays and tropical weather can be!
The picture at the top is of the monsoon on Thong Nai Pan Noi. Below is a little widget to tell you the weather conditions in Koh Phangan at the moment.