Weather in Thailand in August

August climate overview

Daytime highs across Thailand in August run from 28.3°C (Phuket) to 31.4°C (Bangkok). In Bangkok about 100% of August days reach 25°C. Nights average 25.2°C; the coldest 10% of nights in Phuket fall to 25°C or below.

Rainfall in August

Expect around 24 rainy days (1 mm or more) in August, with Koh Samui the driest (19 days) and Krabi the wettest (26 days). The wettest August at Bangkok between 1991 and 2020 was 1995 with 240 mm; the driest was 2004 with 76 mm.

Sea temperature

The sea averages 29.1°C around Thailand in August - warmest at Bangkok (29.4°C). That is comfortable for swimming.

Sunshine and daylight

Around 1.4 hours of sunshine a day on average, out of 12.5 hours of daylight (sunshine estimated from cloud cover).

August against the rest of the year in Thailand

August is the 7th warmest month of the twelve in Thailand. It is 0.3°C cooler than July and 0.3°C cooler in September. The hottest month here is April (32°C) and the coolest December (29°C).

Which part of Thailand in August?

• Most sunshine: Phuket, 1.8 h a day.
• Driest: Koh Samui, about 19 rainy days.
• Warmest sea: Bangkok, 29°C.
• Hottest: Bangkok, 31°C by day.
• Coolest (better for walking and cities): Phuket, 28°C.

What to pack for Thailand in August

Based on the averages: summer clothes for the day; a rain jacket - roughly 24 wet days; swimwear - the sea is 29°C.

Similar weather elsewhere in August

Within 1.5°C of Thailand's August daytime average: Ho Chi Minh City (31°C), Rome (31°C, sea 26°C), Varadero (31°C, sea 30°C), Majorca (31°C, sea 27°C), Valencia (31°C, sea 26°C). See the full ranking for August.

Which coast is the better choice?

Koh Samui has the clearest advantage for a coastal stay: its 19 rainy days compare with 24 in Phuket and 26 in both Krabi and Khao Lak. That makes it the better bet for fewer wet days, not a promise of uninterrupted beach weather. Daytime temperatures are similar across these choices, ranging from 28°C in Phuket and Khao Lak to 29°C in Krabi and Koh Samui, so rain is the more useful deciding factor. The sea is 29°C at all of them. Choose Koh Samui if time by the water matters most; for the other coastal destinations, be especially willing to rearrange outdoor plans.

Bangkok or Chiang Mai?

Bangkok suits travellers who want the hottest conditions, with daytime temperatures of 31°C and nights of 25°C. Keep outdoor plans manageable around midday and allow yourself breaks from the heat; rain does not make this a cool-weather trip. Chiang Mai is less hot by day at 29°C, while its 23°C nights offer more relief than Bangkok's. The catch is rain: Chiang Mai has 26 rainy days against Bangkok's 24. Neither is a strong choice if dry outdoor time is essential. Choose Chiang Mai for cooler evenings, or Bangkok if you prefer hotter days and can keep your schedule flexible.

What to pack and how to plan

Pack for warmth and wet weather rather than for cool evenings. Thailand's average night temperature is 25°C, so light clothing is a more useful starting point than heavy layers. A lightweight waterproof, an umbrella and footwear you can manage in the rain will help keep plans practical. With average sunshine of 1.4 hours, do not build each day around a long spell of sun. Leave room to move outdoor activities when conditions suit, and keep indoor alternatives available. August works best for travellers who value warm conditions and can accept weather-led changes; it is harder to recommend for anyone whose main aim is sunbathing.