Phuket weather by month + Phuket vs Samui vs Krabi: which island, which month
"When is the best time to visit Phuket?" and "Phuket or Samui this month?" are different questions that need the same table — because Phuket and Krabi sit on the Andaman coast, Samui sits on the Gulf, and the two coasts take their monsoons on different schedules. The month one side is at its wettest can be the month the other side is fine.
This page walks Phuket's weather through all 12 months and compares Krabi and Samui in every one of them. Every figure is a 10-year monthly rainfall mean (2016–2025), the same dataset the weather calendar in rooozt's search bar shows, with the same published thresholds: under 50 mm/month = low rain, over 150 mm/month = heavy rain (Samui uses the Surat Thani mainland measuring point — see the limits at the end).
The short answer: which island wins which month
December–April the Andaman side wins clearly (Phuket's driest month is February at 34 mm, Krabi 52 mm). May–September all three areas get rain, but the Samui/Surat side runs lighter than the Andaman in most months (June 154 vs Phuket's 195). October–November is the caution window on both coasts — the Andaman peaks in October (Phuket 290, Krabi 296), then the Gulf takes over (Surat 316 → 300).
The mistake this table catches most often: assuming "New Year = dry season everywhere in the south". That's true only on the Andaman side (Phuket December 140 mm and falling) — the Gulf side still gets 196 mm in December, and even Krabi sits at 154 mm, right on the heavy-rain line.
January–March: full Andaman high season
Phuket runs 78 → 34 → 62 mm, with February the driest month of its year. Krabi tracks the same line (84 → 52 → 77) and the Surat side is driest in the same window (125 → 40 → 53) — the only stretch of the year when all three areas are dry at once. If you can't pick an island yet, pick the month first: February is the hardest one to get wrong.
Temperatures on the southern coasts barely swing compared with the mainland: Phuket's mean maximum stays between 28.8 and 32.3°C all year, peaking in March (32.3°C), while Krabi reaches 34.1°C the same month.
April: the turning month — Phuket holds, Krabi turns first
April puts Phuket at 116 mm, still in the middle band, but Krabi climbs to 154 mm — already touching the heavy-rain threshold — and the Surat side reads 149 mm. For a Songkran beach trip the numbers lean slightly toward Phuket over Krabi, and this is the last month before the southwest monsoon arrives in full.
May–September: Andaman monsoon — Samui is the option the numbers support
Across these five months Phuket averages 178–241 mm a month and Krabi 192–251 mm — in the heavy band almost throughout. The Surat side is visibly lighter in several months: June 154 vs Phuket's 195, August 161 vs 207, with July close (185 vs 178). Overall the Gulf side has the mid-year edge — not dry, just less wet.
One thing that is NOT from our dataset but is common knowledge about the Andaman in monsoon season: winds and swell pick up, many beaches fly red no-swim flags in spells, and some island boat routes stop running — check local notices and listen to people on the ground. The mm in this table measure water volume, not sea state.
October: the Andaman's heaviest month
October is the peak for both Phuket (290 mm) and Krabi (296 mm) — and the Surat side peaks at the same time with 316 mm. It's the one month all three areas go red across the board. If you can avoid one month for the southern islands, this dataset points at October (the lighter numbers that month are on the upper Gulf — see Hua Hin's 232 in the master page).
November–December: the Andaman clears, the Gulf takes its turn
Phuket falls from 246 to 140 mm and Krabi from 274 to 154 mm — by December the Andaman side drops out of the heavy band and rolls into true high season in January. The Surat side is still in it: November 300 mm, December 196 mm. A New Year trip to Samui therefore carries meaningfully more rain risk than Phuket — which is why "which island for New Year?" should start with the Andaman if rain is the only criterion.
What this dataset cannot tell you
Use the table to choose the month and the coast, then use the real forecast to choose the day
- 10-year averages — any single year can differ a lot from the mean
- "Samui" in the table is the Surat Thani mainland measuring point; the island itself can differ. Krabi is the town coordinate, not Phi Phi or Lanta
- Rain in mm says nothing about swell, red flags or cancelled boats — check local notices before going to sea
- Tropical rain tends to come as short storms, not all-day drizzle — a heavy month is not a sunless month
Mean monthly rainfall: Phuket vs Krabi vs Samui (mm/month, 10-year mean)
Same thresholds as rooozt's weather calendar: under 50 mm = low rain, over 150 mm = heavy rain — the table scrolls sideways on mobile
| Area | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Phuket | 78 | 34 | 62 | 116 | 230 | 195 | 178 | 207 | 241 | 290 | 246 | 140 |
| Krabi | 84 | 52 | 77 | 154 | 250 | 192 | 202 | 218 | 251 | 296 | 274 | 154 |
| Samui (Surat Thani point) | 125 | 40 | 53 | 149 | 204 | 154 | 185 | 161 | 237 | 316 | 300 | 196 |
Samui uses the Surat Thani mainland measuring point and Krabi the town coordinate — the islands themselves can differ. A real year can differ a lot from the mean; check the actual forecast close to your travel date.
Official links to check yourself
- Thai Meteorological Department ↗ (opens in a new tab)
The real forecast and marine warnings for the week you travel — our table is an average, not a forecast
Frequently asked questions
- What is the driest month in Phuket?
- February — 34 mm/month on 10-year averages, followed by March at 62 mm and January at 78 mm. The wettest month is October at 290 mm.
- When is the best time to visit Koh Samui?
- At the Surat Thani measuring point the driest months are February–March (40 and 53 mm), and the stretch to treat with most caution is October–December (316 / 300 / 196 mm) — the mirror image of Phuket, which is entering high season at exactly that time.
- Can I visit Phuket in the rainy season?
- Yes — with the numbers in hand: May–October Phuket averages 178–290 mm a month, usually falling as short storms rather than all-day rain. The real caution is swell and red beach flags (general knowledge, not a figure from our dataset). For a lighter mid-year beach, the Samui side runs about 40–50 mm below Phuket in June and August.
- Is Phuket's weather different from Krabi's?
- Barely — both sit on the Andaman coast and their monthly rain tracks together all year. The clearest gap is April (Krabi 154 mm, already touching the heavy band; Phuket 116 mm, still middle). Choose by the islands and activities you want, not by the weather.
Where the numbers come from: Every temperature and rainfall figure in this article is a 2016–2025 monthly mean from the ERA5 dataset (via the Open-Meteo Historical Weather API) at each city's coordinate — a 10-year statistic, not a forecast for your trip. Any single year can differ a lot from the mean. ERA5 is a roughly 9 km reanalysis grid, not a reading from any one weather station. This is the same dataset the weather calendar in rooozt's search bar displays.