When does Phuket's high season really start? The answer from 10 years of monthly rain data
"Phuket high season: Nov–Apr" is repeated so often it feels like fact — but across those six months the rain is nowhere near equal. This article lays out the 10-year monthly rainfall means (2016–2025) at Phuket's coordinate, month by month — the same dataset the weather calendar in rooozt's search bar uses for its colour bands.
The real monthly numbers (mm/month, 2016–2025 means)
In calendar order, the picture looks like this:
- Jan 78 · Feb 34 · Mar 62 — the three driest months of the year, the heart of the Andaman dry season
- Apr 116 — tropical afternoon showers begin, but overall still comfortable
- May–Aug 230 / 195 / 178 / 207 — the southwest monsoon at full strength
- Sep 241 · Oct 290 · Nov 246 — the three wettest months, with October the peak of the year
- Dec 140 — the rain is retreating but not gone: still more than April
How to read this as a trip plan
If the goal is open skies, clear water and boats running almost daily — the golden window is Jan–Mar, with February (34 mm) the driest month of the year, no contest.
December is the busiest month because it lines up with the long holidays, but the numbers say it's the tail end of the monsoon (140 mm), not the driest point — short showers remain a real possibility, traded for festival atmosphere and the year's peak prices.
The opposite corner is Sep–Nov (241–290 mm): room rates drop clearly and the islands are still beautiful, but budget for days when boats can't go out and seas run rough — better suited to resort-stay trips than daily island-hopping.
Booking the dry window well
Rooms in Jan–Mar are almost always better-priced than late December despite better weather — shift a New Year trip to late January when you can, and you get both clearer skies and softer prices. And before paying, always compare the same night across several providers: high season is when identical rooms differ in price the most all year.
Frequently asked questions
- Which months are best for boat trips to Phi Phi / Similan?
- By the rain statistics, the steadiest window for calm seas and open skies is Jan–Mar (34–78 mm/month of rain) — and it's general knowledge that several Andaman marine parks open only in the dry season; check the latest year's announcements before planning.
- Then why does everyone say high season starts in November?
- Because November is when the monsoon starts retreating and travellers start returning — but November's mean is still 246 mm, close to the yearly peak. Atmosphere-high-season and the statistical dry window are simply not the same line; this article gives you the numbers so you can choose which one you want.
Where the numbers come from: Every rainfall figure in this article is a 2016–2025 monthly mean from the ERA5 dataset (via the Open-Meteo Historical Weather API) at each province's coordinate — a 10-year statistic, not a forecast for your trip. Any single year can differ a lot from the mean. This is the same dataset the weather calendar in rooozt's search bar displays.