Phuket & Krabi vs Koh Samui, Nov–Dec 2026: Which Is Drier?

How much does it rain in Phuket, Krabi and Koh Samui from October to January?

Koh Samui gets about two to three times as much rain as Phuket or Krabi in November and December, and the gap narrows, but does not close, in January. The figures below are the Thai Meteorological Department's (TMD) 30-year climate normals for 1991–2020.

• Rain days are TMD's average monthly count of days with at least 0.1 mm of rain. The WMO version of the same normals, which counts only days with at least 1 mm, gives fewer: Phuket 12.9 and Koh Samui 16.5 in November.
• November is the wettest month of the year on Koh Samui (444.6 mm, about 22% of its 1,994 mm annual total). On the Andaman side the peak is September–October.
• Phuket Airport, on the island's northwest coast, is wetter than Phuket town: 219.0 mm in November and 86.4 mm in December (WMO 1991–2020).
• A rain day in the tropics often means a heavy shower or storm, not rain all day.

Is November already dry season in Phuket and Krabi?

Not completely. November is the month the Andaman coast changes over: rain falls by about a third (Krabi) to a half (Phuket) compared with October, but Phuket and Krabi still average 178–199 mm and 16–18 rain days. December is the first month that is reliably dry.

• Early November: expect regular afternoon or evening storms, and some days when the sea is rough. Book flexible tours.
• Late November to December: usually calm enough for island-hopping, and the normals drop to 82–90 mm.
• Boat-trip parks are usually open: Maya Bay on Phi Phi Leh closes in August–September and was reported reopened on 1 October 2026 (no swimming in the bay). The Similan Islands usually open mid-October to mid-May. Check each park's notice before you book.
• A Phi Phi speedboat day trip from Phuket is the easiest way to see Maya Bay. Operators can cancel or move trips when TMD issues a marine warning, so keep a spare day in your plan.

2026 so far (as of 3 Nov 2026): TMD has issued a series of "heavy to very heavy rains in the South" advisories in late October and early November. Advisory No. 4 (287/2026), issued on 3 November, forecasts more rain in the South on 7–9 November and waves above 2 metres in thundershowers in both the Andaman Sea and the Gulf of Thailand.

Should you skip Koh Samui in November and December?

Avoid November if beach weather is your priority. In an average year, November is Koh Samui's wettest month and December is still wetter than any Andaman month after October. The northeast monsoon pushes rain onto the Gulf coast from about November until it eases in January.

• November: 444.6 mm over 18.7 rain days, the island's peak. Ferry crossings and snorkel trips are the first to be cancelled when the sea turns rough.
• December: 263.1 mm. TMD's seasonal outlooks note that the heaviest Gulf-coast rain tends to fall in the first half of the month.
• January: 126.8 mm over 11.1 rain days. Usually fine for a beach trip, but still wetter than Phuket.
• If you go anyway: book hotels with free cancellation and leave a buffer day before an onward flight.

Last year followed the same pattern. In November 2025, TMD recorded 311.3 mm of rain on the southern east coast and 188.0 mm on the west coast (91% and 97% of normal).

How do you stay safe on beaches and boats in the rainy months?

Never swim when a red flag is up, and stay off boats when TMD issues a marine warning. Both coasts can have dangerous seas in these months. The UK Foreign Office (FCDO) warns that people have drowned in strong riptides in Thailand, and that boats have sunk or collided because of overloading, poor maintenance and rough seas, especially in the monsoon season.

• Beaches: lifeguards work at designated beaches and use a flag system. Follow all warning signs, especially red flags. Phuket's west-coast beaches can still have rough surf in early November.
• Boats: don't board a boat that looks overloaded or has no life jackets.
• Warnings: TMD's English warnings page lists wave heights for the Andaman Sea and the Gulf. When it says waves will exceed 2 metres, expect boat-trip cancellations.
• Stay online: a Thailand 5G eSIM lets you check TMD warnings and operator messages on a beach or pier.
• Emergencies: see our Thailand emergency numbers guide for the Tourist Police and ambulance numbers.

General information only. Check TMD, your tour operator and official sources for your situation.