Rainy Season in Thailand: Month by Month

Quick answer: Thailand’s rainy season runs May–Oct in Bangkok and the north, and September is the wettest month in both Bangkok (299 mm (11.8 in)) and Phuket (358 mm (14.1 in)). The dry months are Nov–Mar — Bangkok’s December averages 8 mm (0.3 in) across 2 rain days. Phuket is far the wettest place here, 2647 mm (104.2 in) a year against Bangkok’s 1434 mm (56.5 in), and its rain carries a month later, through November.

Pick a destination to see its weather month by month and the best time to go, or pick a month to see where the weather is at its best.

Start from

Destination

Best = an ideal daily high for the kind of trip and rain on 10 days or fewer; the rule is under the tool.

Tokyo · a city trip

Good: Mar–May, Oct–DecNo month is ideal for a city trip by our rule, but these come close.

Warmest: Aug · 89°F
Coolest: Jan · 49°F
Wettest: Jul · 16 rain days

Averages for 2006–2025: any single year can be hotter, colder or wetter.

Weather from NASA POWER daily data, 2006–2025, for the ~50 km area around each place. Right on the coast, afternoons can be a few degrees warmer than shown.

Month	High / low (°F)	Rain days	Rain (in)	Verdict
Jan	49° / 34°	5	2.4	Off (too cold)
Feb	51° / 35°	7	3.1	Off (too cold)
Mar	57° / 40°	12	5.1	Good (cool, showery)
Apr	65° / 48°	12	6	Good (showery)
May	73° / 58°	13	6.6	Good (showery)
Jun	79° / 65°	16	8.1	Off (too wet)
Jul	86° / 73°	16	6.5	Off (too wet)
Aug	89° / 75°	15	5.4	Off (too hot)
Sep	82° / 70°	16	8.7	Off (too wet)
Oct	72° / 59°	14	8.9	Good (showery)
Nov	63° / 48°	11	4.4	Good (showery)
Dec	54° / 39°	7	3.2	Good (cool)

The tool above opens on Bangkok: change the place or the month to yours, or compare Phuket and Chiang Mai. Below, Thailand month by month — rain, rain days and how warm it is.

Thailand month by month

Average rainfall and the number of days with at least 1 mm of rain, 2006–2025. On this page a month counts as wet when it gets more rain than an average month in that place (more than a twelfth of its year), and dry when it gets less than half an average month. The months in between are the shoulder.

Month	Bangkok	Phuket	Chiang Mai	Bangkok: rain
January	3 days — dry	13 days — dry	2 days — dry	15 mm (0.6 in)
February	4 days — dry	8 days — dry	2 days — dry	17 mm (0.7 in)
March	7 days — dry	14 days — dry	4 days — dry	39 mm (1.5 in)
April	13 days — shoulder	23 days — shoulder	11 days — shoulder	80 mm (3.1 in)
May	22 days — wet	29 days — wet	22 days — wet	173 mm (6.8 in)
June	24 days — wet	27 days — wet	22 days — wet	160 mm (6.3 in)
July	26 days — wet	27 days — wet	26 days — wet	187 mm (7.4 in)
August	26 days — wet	27 days — wet	27 days — wet	197 mm (7.8 in)
September	27 days — wet	28 days — wet	23 days — wet	299 mm (11.8 in)
October	23 days — wet	29 days — wet	18 days — wet	214 mm (8.4 in)
November	9 days — dry	27 days — wet	6 days — dry	45 mm (1.8 in)
December	2 days — dry	20 days — shoulder	2 days — dry	8 mm (0.3 in)

Bangkok is wet in May–Oct, shoulder in Apr and dry in Nov–Mar. Phuket is wet in May–Nov, shoulder in Apr, Dec and dry in Jan–Mar. Chiang Mai is wet in May–Oct, shoulder in Apr and dry in Nov–Mar.

The Gulf islands run on a different calendar and nothing on this page speaks for them. Koh Samui, Koh Phangan and Koh Tao face east, and their wettest months are October to December — while Phuket and the Andaman coast are drying out. The three places here are the Andaman coast, the central plain and the north.

The wettest and driest months

Bangkok: wettest in September (299 mm (11.8 in), 27 rain days), driest in December (8 mm (0.3 in), 2 rain days). Phuket: wettest in September (358 mm (14.1 in), 28 rain days), driest in February (41 mm (1.6 in), 8 rain days). Chiang Mai: wettest in August (247 mm (9.7 in), 27 rain days), driest in February (10 mm (0.4 in), 2 rain days). Over the year, Bangkok gets 1434 mm (56.5 in).

The best months to go

Bangkok: Nov–Dec · Phuket: Feb · Chiang Mai: Nov–Jan. When to Go rates every month on temperature, rain days and storms — open Bangkok in the tool above and step through the year.

Plan it

FAQ

When is the rainy season in Thailand?

May–Oct — the months that get more rain than an average month in Bangkok. September is the wettest, at 299 mm (11.8 in) across 27 rain days, against 8 mm (0.3 in) in December (NASA POWER, 2006–2025).

Does it rain all day in the rainy season in Thailand?

The measure here is a day with at least 1 mm of rain, not a day of rain. In September, Bangkok averages 27 rain days out of 30, with an average high of 87°F / 31°C.

What is the driest month in Thailand?

December, at 8 mm (0.3 in) across 2 rain days. The dry months, by the rule this page uses, are Nov–Mar.

When is the best time to visit Thailand?

When to Go rates Nov–Dec the best months for Bangkok, on temperature, rain days and — where it applies — storms. The other places on this page have their own; open the tool above on each.

Which month should I avoid in Thailand?

September, if you are going anywhere on this page: it is the wettest month in Bangkok (299 mm (11.8 in)), Phuket (358 mm (14.1 in)) and close to it in Chiang Mai, whose peak is August at 247 mm (9.7 in).

Is Chiang Mai dry when Phuket is wet?

Not in the rainy season — they overlap almost exactly, May–Oct against May–Nov. The difference is scale: Chiang Mai’s year is 1307 mm (51.5 in) and Phuket’s is 2647 mm (104.2 in). Chiang Mai’s dry months are the drier pair, at 10 mm (0.4 in) in February against Phuket’s 41 mm (1.6 in).

How these numbers are made

Daily rainfall and temperature from NASA POWER (MERRA-2), averaged over 2006–2025; a rain day is a day with at least 1 mm. POWER works on a grid of about 50 km, so each place here is its neighbourhood rather than its own rain gauge: a coast, a small island or a valley under a mountain can differ from the square it sits in. The months are the part that holds; treat a single millimetre figure as an average, not a forecast.