The short answer: November to April is the dry season and the best window for Racha Island. Seas are generally calmest from December to April, and early November can still be mixed. May to October is the wet season, with September and October the wettest months. The snorkeling day still runs in the wet season, but sea conditions decide it day by day.
Racha Noi and Racha Yai sit well offshore, so the weather and the sea matter more here than on a short hop to the Khai Islands. Here is what to expect, month by month, and what we do when conditions are not good enough to go.
| Month | Avg. rain days | Season and sea conditions |
|---|---|---|
| January | 5 | Peak season. Generally calm |
| February | 3 | High season. Generally calm |
| March | 5 | High season. Generally calm |
| April | 11 | Hot, with more rain. Generally calm |
| May | 21 | Wet season starts. Rougher, varies by day |
| June | 19 | Wet season. Rougher, varies by day |
| July | 20 | Wet season. Rougher, varies by day |
| August | 19 | Wet season. Rougher, varies by day |
| September | 23 | Wettest month. Often the roughest |
| October | 22 | Wet season. Often rough |
| November | 16 | Transition month. Mixed, can be a bit rough early on |
| December | 8 | Peak season. Generally calm |
Rain-day averages and season labels are general Phuket figures from Phuket101. The sea-condition notes describe Phuket's Andaman coast in general, not measurements taken at Racha.
May to October is the wet season. Rain often comes as showers, and not every day is a washout. The bigger question for a boat day is the sea: the Thai Meteorological Department regularly issues Andaman Sea warnings in the wet season. For example, its warning of 29 May 2026 gave waves of 2–3 metres in the upper Andaman Sea and advised small boats to stay ashore.
Tour boats around Phuket can be delayed or cancelled at short notice when conditions require it, and the decision rests with the boat's captain.
If conditions are not good enough for a safe, enjoyable day at Racha, we decide what to do. Depending on how severe the conditions are, we may refund your booking, move it to another day, or change the day to a different island. We do not run a trip we do not think is right just to keep the schedule.
The Thai Meteorological Department publishes current warnings for the Andaman Sea, including expected wave heights, at tmd.go.th. If you are booking during the wet season and want to know how your date looks, message us on WhatsApp or LINE before you commit.
Not as a rule. The trip runs in the wet season (May to October) when conditions allow, and it is decided day by day. Some days are fine, others are not.
We make the call. Depending on how severe conditions are, we may refund your booking, move it to another day, or change the day to a different island.
November to April is the dry season and the best window. Seas are generally calmest from December to April, while early November can still be mixed.
Racha Noi is the furthest stop, so the crossing is where swell is felt most. That is one reason the trip runs on a large motor yacht rather than a speedboat.
Ready to look at dates? See the full itinerary, inclusions and pickup areas on our Racha Island Snorkeling & Yacht tour.