Phuket Weather, Month by Month

Most weather pages for a tropical island lead with temperature. That is the wrong variable here, and saying so is the fastest way to understand Phuket’s year.

Phuket sits at about eight degrees north. It has no cool season, no shoulder in the way a Mediterranean island has one, and almost no annual temperature swing: the difference between the warmest and coolest month is a couple of degrees, and it is hot in all of them. What changes across the year, and changes enormously, is how much rain falls and what the sea is doing. Those are the two numbers on this page.

Rainfall, measured at Phuket

These are thirty years of ERA5 reanalysis data, 1995 to 2024, averaged per calendar month at the island’s own west-coast coordinates rather than borrowed from a national figure.

The shape is a single wet season with a sharp start and a slower end. March to May is the change that catches people: 93mm, then 152mm, then 269mm in three consecutive months, with rain days going from twelve to twenty-five.

What 28 rain days actually looks like

This is the number that frightens people out of a monsoon trip, and it deserves qualifying. October has rain on 28 days out of 31, which sounds like a washout and mostly is not. Tropical rain here arrives as a heavy afternoon downpour that lasts an hour or two and then stops. A day with 10mm and a day with 60mm both count as one rain day, and October’s total is not spread evenly.

What does genuinely change, and what the rain-day count hides, is the sea.

The sea, which is the real seasonal variable

Phuket’s famous beaches are all on the west coast, and the southwest monsoon arrives from exactly that direction. Four years of marine reanalysis at each beach, averaged as the mean daily maximum wave height per month, in metres:

Two things fall out of that table. The first is the scale of the seasonal change: the same beach goes from half a metre to well over a metre and back again, and a metre of wave on a beach with no reef in front of it is a different proposition entirely.

The second is a gradient nobody mentions. The west coast gets steadily calmer as you go north. Kata at the southern end is the roughest beach on the island in every month of the year; Mai Khao at the northern end is the calmest, and the difference between them is about forty per cent. If the sea matters more to you than the nightlife, that is the single most useful line on this page.

Red flags, and why they are not decoration

Drowning is one of the two causes of visitor deaths in Thailand that is not crime, and Phuket’s west-coast beaches during the monsoon are where a large share of it happens. Rip currents in these months are strong enough to be fatal, lifeguard coverage is thin, and the red flags mark exactly the beaches and the days where that is true.

The rule is simple and people break it constantly because the sea looks calm from the sand: if the flag is red, do not go in. A rip is not visible from the beach and it does not pull you under, it pulls you out.

Choosing a month

December to March is the dry season and there is no argument about it. February is the best of the four on every measure. December is the value month until about the 20th, after which prices go to their annual maximum and stay there into January.

April is an odd month worth understanding. Rainfall has jumped to 152mm, but the sea is still at its calmest of the entire year, at 0.47m off Patong. If you want flat water and can accept afternoon rain, April is underrated. It is also the hottest month and it contains Songkran.

May to October is the monsoon, and the honest advice is not to come to Phuket in it if the beach is the point. Prices are at their lowest and the island is genuinely quiet, which suits some trips. If your dates fall in these months and you want a beach, the Gulf coast is in its dry season and is the better answer.

November improves noticeably through the month. The first half is still wet at the tail of the monsoon; the second half is often the first good fortnight of the season and it is priced as if it were not.

How these figures were made

Rainfall is ERA5 reanalysis, 1995 to 2024, thirty full years averaged per calendar month at Phuket’s west-coast coordinates. A rain day is a day with a millimetre or more. Wave height is open-meteo’s marine reanalysis, which begins in 2022, so it is four years rather than thirty and shows a seasonal shape rather than an unusual year.

There is no temperature table on this page and that is deliberate. The reanalysis grid cell covering Phuket is mostly sea, which suppresses the daily maximum by several degrees, and a figure we cannot stand behind is worse than a gap. The honest summary is the one above: it is hot here every month, and the month decides the rain and the sea rather than the heat.