Strong monsoon to drench six southern provinces; Northeast to cool by 2–4°C

Thailand’s Meteorological Department (TMD) warned on Thursday, December 25, 2025 that the strengthening northeast monsoon will bring more rain to the lower South, with heavy downpours forecast in Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala and Narathiwat.

Residents in the lower South were urged to watch for heavy rainfall and accumulated rain that could trigger flash floods and runoff, especially on mountain slopes near waterways and in low-lying areas.

The TMD also advised mariners to navigate with caution in the Gulf of Thailand and the Andaman Sea, and to avoid sailing in thunderstorm areas.

Sea conditions

Lower Gulf of Thailand: waves around 2 metres

Upper Gulf of Thailand: waves 1–2 metres

Thunderstorm areas: waves around 2 metres (and locally higher)

Another cold air mass to hit upper Thailand

The department said a relatively strong high-pressure system (cold air mass) from China has already covered Laos and northern Vietnam, and is expected to spread over upper Thailand tonight (December 25).

Upper Thailand is forecast to see stronger winds and a drop in temperatures, with people advised to take care of their health in colder conditions and remain alert to fire risks due to dry, windy weather.

Dust and haze

In the Central region, including Bangkok and surrounding provinces, dust/haze accumulation is expected to be moderate to relatively high due to poor ventilation. Other regions are forecast to remain good to moderate.

Forecast (6pm today to 6pm tomorrow)

North
Cool with morning fog. Low 15–20°C, high 30–35°C. Mountaintops cold to very cold with isolated frost; low 4–12°C.

Northeast
Cool to cold in the morning with strong winds; temperatures down 2–4°C. Low 14–20°C, high 29–34°C. Mountaintops cold; low 10–14°C.

Central
Cool mornings with strong winds; temperatures down 1–3°C. Low 19–21°C, high 33–34°C.

East
Cool mornings with strong winds; temperatures down 1–2°C. Low 19–23°C, high 32–34°C. Sea about 1 metre, offshore 1–2 metres.

South (east coast)
Thunderstorms in 40% of areas, with heavy rain in places—especially Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala and Narathiwat. Low 20–23°C, high 32–34°C.

From Nakhon Si Thammarat northwards: winds 15–35 km/h, waves 1–2 metres, over 2 metres in storms

From Songkhla southwards: winds 20–35 km/h, waves around 2 metres, over 2 metres in storms

South (west coast)
Partly cloudy; thunderstorms in 10% of areas, mainly Trang and Satun. Low 21–23°C, high 32–34°C. Waves around 1 metre, higher offshore; over 2 metres in storms.

Bangkok and vicinity
Cool mornings with strong winds; temperatures down 1–2°C. Low 22–23°C, high 34–35°C.