Phuket’s low season, also called the green or rainy season, is the time of the southwest monsoon over the Andaman Sea, from May to October. Below are Thai Meteorological Department (TMD) normals, hotel occupancy from the Ministry of Tourism and Sports (MOTS) and national park rules, checked on 17 October 2026.
Low season weather by month
TMD normals for 1991-2020 at the Phuket town station. A rain day is any day with 0.1 mm or more; occupancy is for Phuket hotels in 2025 (MOTS).
| Month | Rain, mm | Rain days | Daytime high, °C | Hotel occupancy 2025, % |
|---|---|---|---|---|
| May | 236.9 | 18.9 | 33.2 | 73.95 |
| June | 249.4 | 18.6 | 32.6 | 66.79 |
| July | 240.2 | 19.1 | 32.3 | 70.68 |
| August | 308.7 | 19.5 | 32.2 | 68.90 |
| September | 350.4 | 21.7 | 31.8 | 65.84 |
| October | 336.0 | 22.7 | 31.8 | 77.64 |
| For comparison: January | 49.9 | 5.6 | 33.0 | 86.41 |
It is hot all year; what changes is rain and sea state. November is a transition month with half of October’s rain. In 2026 TMD declared the rainy season open on 15 May, and Phuket saw flooding on 18-20 May: low streets flood for a few hours after a heavy downpour.
Waves and red flags
From May to October the wind comes from the west, and Phuket’s west coast faces the open Andaman Sea. Local municipalities say so plainly: strong waves at Nai Harn from May to October, “fairly strong” waves at Karon. Rip currents are the bigger danger.
A red flag means no swimming. What to do if a current pulls you out is in red flags and rip currents. For calmer spots, see Phuket beaches without waves.
What closes: national parks
| National park | Closed | Open | Source |
|---|---|---|---|
| Similan Islands | 16 May-14 October | 15 October-15 May | DNP |
| Surin Islands | 16 May-14 October per recent DNP season notices | 15 October-15 May, some bays closed | DNP |
DNP explains that monsoon wind and waves make trips unsafe. These are the standing dates on the park pages; a given year can open earlier or later by separate announcement, so check before booking. The day trip is covered on our Similan Islands page.
Other boat trips are not banned outright, but boats cancel when a storm warning is issued. Avoid non-refundable ferry tickets for a day with a warning.
Things to do in the rainy season
- Swim in sheltered bays and on the east coast, and always check the flag
- Walk the Phuket Old Town and sit out the downpour in a cafe
- Visit the Big Buddha in the morning, which is more often dry
- Plan island days with spare days in case a boat is cancelled
- Learn to surf: Karon municipality notes surfers at Kata
Who low season does not suit
Anyone coming for the Similans, which are closed. Anyone who wants calm sea every day right in front of a west coast hotel. And anyone with only a few days and a rigid excursion plan.
Related: Phuket in October: weather, waves and what is open.
FAQ
Is it worth visiting Phuket in the rainy season?
Yes, if you accept that the sea on the west coast is often rough and some island trips get cancelled. It rains most days, but usually as a downpour rather than a grey day. Hotels are quieter: 65.8% occupancy in September 2025 against 86.4% in January.
When is the rainy season in Phuket?
According to TMD, the southwest monsoon that brings rain to the Andaman coast blows from May to October. In 2026 the rainy season started on 15 May. Under the 1991-2020 normals, September and October are the wettest months with 336-350 mm.
Can you swim in Phuket during low season?
Yes, but choose your beach and watch the flags. Rawai municipality warns of strong waves at Nai Harn from May to October. Sheltered bays and the east coast are calmer; never enter the water under a red flag.
Which islands are closed in the rainy season?
The Department of National Parks lists Mu Ko Similan National Park as closed from 16 May to 14 October (an older DNP park page still says 31 October). Recent DNP season notices close the Surin Islands on the same dates, 16 May to 14 October, and some Surin bays stay closed in season because of coral bleaching. The reason given is monsoon wind and waves. Check DNP announcements for the exact reopening date in a given year.
Does it rain all day in Phuket in October?
TMD counts 22.7 rain days in October, but a rain day starts at 0.1 mm. Often it is a short tropical downpour. Weather apps show a rain icon for the whole day, which looks worse than it is.
Sources
- TMD. Climatological Data for the Period 1991-2020 (printed pp. 82-83)
- TMD. Monthly climate summary, May 2026
- TMD. Seasons of Thailand
- MOTS. Tourism statistics by province, 2025 (xlsx)
- DNP. Mu Ko Similan National Park
- DNP. Mu Ko Surin National Park
- Krungthep Turakij. DNP opens Similan, Surin and Laem Son season to 15.05.2025 (17.10.2024), media
- Rawai Municipality. Nai Harn Beach
- Karon Municipality. Karon Beach
Found an error or outdated fact? Tell the editors, we will fix it and update the check date.