Thailand in December: Rain in 77 Provinces (+ January)

Measured by rain, December is one of the driest months of the year for most of the country. 24 provinces average 10 mm or less for the whole month, and 18 of them are in the northeast. The median province in each region gets: Northeast 6 mm, Central 14 mm, North 16 mm, East 17 mm, West 21 mm and South 183 mm (ERA5 2016–2025).

The south is where plans go wrong. December is not yet the dry season there. The northeast monsoon pushes its heaviest rain onto the lower Gulf coast in November and December, while the Andaman side is moving into its dry season but is not dry yet. The two coasts get their own sections below.

• Clearest skies: the northeast, median 6 mm and 1 rainy day
• Coolest: the north, median overnight low 17.7°C
• Driest beaches: the east coast and upper Gulf, 17–37 mm (Chonburi to Prachuap)
• Wettest: the lower Gulf and the deep south, 122–407 mm

All 20 provinces of the northeast (Isan) average 11 mm of December rain or less. The driest are Bueng Kan at 2 mm and Udon Thani at 3 mm, and the median Isan province sees just 1 rainy day all month. The median overnight low is 19.0°C, about 3.5 degrees cooler than Bangkok.

The Mekong towns of Nakhon Phanom, Nong Khai and Bueng Kan get both clear skies and cool mornings. Nakhon Phanom's average December low is 16.9°C, close to Chiang Mai's 17.5°C, with only 4 mm of rain against Chiang Mai's 25 mm. For a cold ranking of 21 provinces, see our page on where Thailand actually gets cold.

The 9 northern provinces get 8–29 mm in December, median 16 mm, a little wetter than Isan. Chiang Rai is the wettest in the region at 29 mm but also the coldest, with an average low of 15.9°C and an average daytime high of only 26°C.

These figures are for each town's coordinate. Mountain tops are always several degrees colder; our roughly 9 km grid cannot resolve summits, so treat the numbers as a floor and pack a jacket.

The east coast is the driest coastline of the month: Chonburi 17 mm, Rayong 23 mm, Chanthaburi 19 mm, Trat 30 mm, on 3–5 rainy days.

Pattaya has no point of its own in our data, so we give a range from its two nearest reference points, Chonburi and Rayong: 17–23 mm. Koh Samet and Koh Chang use the Rayong and Trat provincial figures; the islands themselves may differ.

Hua Hin and Cha-am use two reference points, Phetchaburi at 21 mm and Prachuap Khiri Khan at 37 mm. Prachuap is the wettest province outside the south in December, yet it still averages only 5 rainy days.

In January Prachuap rises to 63 mm, the most of any province outside the south. If you can choose between the two months, Hua Hin is drier in December.

Yes, though less than in November. The 6 Andaman provinces get 88–170 mm in December on 10–19 rainy days: Phuket 140 mm, Krabi 154 mm, Phang Nga 131 mm. That is about 40–45% less than November (Phuket's November is 246 mm).

By January the Andaman side falls to 78–86 mm, with Phuket at 78 mm. If an Andaman beach trip can move, late December to January is a better bet than early December. Rainy days in the table count every day with 1 mm or more; on this coast many are short showers rather than all-day rain (a general observation, not a figure from the dataset).

The 8 provinces of the lower Gulf and the deep south (including inland Phatthalung and Yala) get 122–407 mm in December on 12–25 rainy days. Narathiwat (407 mm), Songkhla (375 mm) and Nakhon Si Thammarat (347 mm) are the three wettest provinces of the month.

Koh Samui has no point of its own in our dataset; the nearest is mainland Surat Thani at 196 mm, and the island may differ. If Samui over New Year is the plan, our Phuket or Samui for Christmas page already compares rain with rooms left night by night.

The 22 central provinces get 10–22 mm in December. Bangkok averages 19 mm on 4 rainy days, with a daytime high of 31.1°C and a low of 22.5°C; Ayutthaya gets 13 mm. Walking open-air temples is easier than in other months, but afternoons are still above 30 degrees.

The west is just as dry: Tak 11 mm, Kanchanaburi 15 mm, Ratchaburi 23 mm. Every province is in the 77-province table below.

It depends on the region. Outside the south, January is slightly wetter than December in 48 of 63 provinces, but the amounts stay very small (61 of 63 are still under 40 mm), and January is colder than December in 69 of 77 provinces. If cool weather is the goal, January has the edge.

The south is the reverse: January is drier than December in all 14 southern provinces. The Andaman side drops from 88–170 to 78–86 mm and the lower Gulf from 122–407 to 90–223 mm. For a southern beach trip, January is the better month.

Five things the figures on this page support directly.

• Going north or into the hills: bring a warm layer for town mornings below 18°C, and colder still at altitude
• Going to the Andaman coast: allow for short rainy spells on about half the days, and leave boat trips room to move
• Going to Samui or the lower Gulf: choose free-cancellation rooms or travel insurance, since this is that region's wettest stretch of the year
• Around New Year: check official announcements about public celebrations before booking outdoor events (an important royal ceremony takes place in mid-December 2026)
• Close to departure: check the real forecast from the Thai Meteorological Department, because this table is a 10-year average, not a forecast

rooozt uses the same 10-year ERA5 means as the weather calendar in its search bar; every figure here was read from our data file on 13 October 2026.

• Not a weather forecast; a real year can differ a lot from the mean
• Values are at each province's town coordinate, not on islands or mountain tops
• It says nothing about wave height or swimming bans; follow provincial and Thai Meteorological Department notices
• Not a list of things to do, and no province paid to appear on this page