Thailand Weather and Seasons — The 2025 Guide for Australians

Temperature: 35–42°C in central and northern Thailand. Chiang Mai can hit 42°C in April. Bangkok is hot and humid. This is the hardest season for new arrivals not acclimatised to tropical heat. Rainfall: low to nil. The north is at its driest. Chiang Mai burning season: March–April is when northern Thai farmers burn their fields. Combined with dry conditions and trapped smoke in the mountain bowl, Chiang Mai's AQI during March–April can reach hazardous levels (AQI 200–400). Respiratory conditions are severely worsened. Many Chiang Mai expats leave for this period (beach locations or overseas).

Recommendation for Australians: unless you have to arrive March–May, don't plan your initial settlement during this period. Acclimatising during hot season while simultaneously learning the city is more difficult than necessary.

Temperature: lower than hot season — 27–33°C. Humidity is high. Rainfall: afternoon and evening showers (not all-day rain as many assume). Most days have sunshine for part of the day. The rains typically arrive in the afternoon. Floods: Bangkok and Chiang Mai experience periodic flooding during heavy rain. September–October is when flooding risk is highest. Benefit: prices for accommodation and flights drop 20–30%. Tourist crowds thin significantly. Nature is at its most vibrant — rice fields green, waterfalls flowing.

Australians arriving during the wet season often find it more manageable than expected — the rain cools things down and the heat is less oppressive than the hot season.

The peak season. Cool, dry, and the most comfortable weather in Thailand. Temperature: 18–28°C in Chiang Mai (genuinely cool at night — pack a light jacket). 25–32°C in Bangkok. 27–33°C in Phuket. Rainfall: very low. Clear skies.

This is the season when Thailand is most crowded and most expensive. Christmas and New Year in Phuket, Koh Samui, and Bangkok brings the highest hotel and accommodation prices of the year.

Recommendation: November–February is the best time to arrive and settle. Good weather, lower acclimatisation burden, and easy to explore your new city.

The Andaman coast (Phuket, Krabi, Koh Lanta) and the Gulf coast (Koh Samui, Koh Phangan, Hua Hin) have OPPOSITE wet seasons:

| Period | Andaman coast (Phuket/Krabi) | Gulf coast (Koh Samui/Hua Hin) | |---|---|---| | Nov–April | Dry season (best) | Dry to slightly wet | | May–Oct | Rainy season | Dry, good weather | | Oct–Nov | Transitional | Heaviest rains of the year |

Practical: if Phuket is in its rainy season (June–September), Koh Samui is typically sunny. Expats in Phuket often visit the Gulf coast during the Andaman wet season, and vice versa. This makes the two coasts complementary.

April 13–15 (extended in some cities). Nationwide water fights. Chiang Mai has the most famous Songkran celebration. If you are in Thailand during Songkran, expect to get wet if you go outside in major cities during the festival days. Protect electronics. The festivity is genuine and joyful — most Australians enjoy it.

If arriving to settle long-term: Best arrival months: November–January (cool season, easy acclimatisation) Months to plan carefully around: March–April (extreme heat + Chiang Mai burning season) Months that are fine but require preparation: June–September (wet season — bring rain jacket, expect afternoon showers)

The annual rhythm becomes intuitive within 1–2 years. Most long-stay Australians develop a calendar of when to be in Thailand vs when to travel (Europe in European summer, Australia for family visits, or sea-coast Thailand during Chiang Mai burning season).

General guidance only. Weather patterns vary annually. For current conditions: Weather Underground, Windy.com, or the Thai Meteorological Department (tmd.go.th).