Upper Thailand faces heavy rain, Bangkok afternoon storms
Bangkok faces afternoon and evening thunderstorms, while upper Andaman waves may exceed three metres and small boats should remain ashore
Heavy rain is forecast in parts of northern, upper northeastern and eastern Thailand on Wednesday (August 26, 2026), while thunderstorms are expected across 40% of Bangkok and surrounding provinces, mainly from the afternoon into the evening.
The Thai Meteorological Department (TMD) advised people in affected areas to remain alert to hazards caused by heavy and accumulated rainfall.
A rather strong south-westerly monsoon is prevailing over the Andaman Sea, Thailand and the Gulf of Thailand. A weak monsoon trough also extends across upper Myanmar and upper Laos towards Tropical Storm Narra over the Gulf of Tonkin.
The 24-hour regional forecast covers the period from 6am on Wednesday to 6am on Thursday (August 27).
Rough seas and small-boat warning
Waves in the upper Andaman Sea will be two to three metres high and may exceed three metres during thunderstorms.
The upper Gulf of Thailand will have waves of about two metres, rising above two metres in stormy areas.
Mariners in the Andaman Sea and the Gulf of Thailand should proceed with caution and avoid sailing through thunderstorms. Small boats in the upper Andaman Sea should remain ashore during this period.
Tropical Storm Narra is forecast to make landfall in southern Guangxi, China, on Wednesday.
Travellers planning to visit the affected part of China were advised to check weather conditions before setting out.
Regional forecast
Bangkok and surrounding provinces
- Thunderstorms are forecast across 40% of the area, mainly between the afternoon and evening.
- Minimum temperature: 26–27°C
- Maximum temperature: 33–35°C
- South-westerly winds: 10–25 kilometres per hour
North
- Thunderstorms are expected across 40% of the region, with isolated heavy rain in Mae Hong Son, Chiang Rai, Phayao, Nan and Tak.
- Minimum temperature: 23–27°C
- Maximum temperature: 30–34°C
- South-westerly winds: 10–20km/h
Northeast
- Thunderstorms are forecast across 40% of the region, with isolated heavy rain in Bueng Kan, Sakon Nakhon, Nakhon Phanom and Mukdahan.
- Minimum temperature: 24–25°C
- Maximum temperature: 29–34°C
- South-westerly winds: 10–25km/h
Central region
- Thunderstorms are expected across 40% of the region, mainly in Nakhon Sawan, Uthai Thani, Kanchanaburi and Ratchaburi.
- Minimum temperature: 23–26°C
- Maximum temperature: 33–35°C
- South-westerly winds: 10–25km/h
East
- The East has the country’s widest forecast thunderstorm coverage at 60%, with isolated heavy rain in Nakhon Nayok, Prachin Buri, Chanthaburi and Trat.
- Minimum temperature: 24–28°C
- Maximum temperature: 30–34°C
- South-westerly winds: 20–35km/h
- Waves: about two metres, rising above two metres during thunderstorms
South, east coast
- Thunderstorms are forecast across 30% of the region, mainly in Surat Thani, Nakhon Si Thammarat, Songkhla, Yala and Narathiwat.
- Minimum temperature: 23–26°C
- Maximum temperature: 31–36°C
- From Surat Thani northwards: south-westerly winds of 20–35km/h, with waves of one to two metres, about two metres offshore and above two metres during thunderstorms
- From Nakhon Si Thammarat southwards: south-westerly winds of 15–35km/h, with waves of about one metre, rising to one to two metres offshore and above two metres during thunderstorms
South, west coast
- Thunderstorms are expected across 60% of the region, mainly in Phuket, Krabi, Trang and Satun.
- Minimum temperature: 23–27°C
- Maximum temperature: 31–33°C
- From Phuket northwards: south-westerly winds of 20–40km/h, with waves of two to three metres and above three metres during thunderstorms
- From Krabi southwards: south-westerly winds of 15–35km/h, with waves of one to two metres and above two metres during thunderstorms
