Four Thai regions face heavy rain under strong monsoon

THURSDAY, AUGUST 13, 2026
Four Thai regions face heavy rain under strong monsoon

Bangkok faces thunderstorms across 60% of the area, while waves in the upper Andaman Sea and upper Gulf may exceed three metres in storms

Heavy rain is forecast in parts of northern, upper northeastern, central and eastern Thailand on Thursday (August 13), with a rather strong south-westerly monsoon also bringing rough conditions to the Andaman Sea and Gulf of Thailand.

The Thai Meteorological Department (TMD) warned that heavy and accumulated rainfall could trigger flash floods and run-off, particularly on foothill slopes near waterways and in low-lying areas. 

Bangkok and surrounding provinces are expected to see thunderstorms across 60% of the area, with isolated heavy rain.

The conditions are being driven by a monsoon trough extending across the upper North, Laos and upper Vietnam, combined with the rather strong south-westerly monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand.

Rough seas and waves above three metres

Winds and waves in the upper Andaman Sea and upper Gulf of Thailand are expected to remain rather strong, with waves of 2–3 metres and above three metres in thunderstorm areas.

Mariners have been advised to proceed with caution and avoid sailing in areas affected by thunderstorms.

Small boats in the upper Andaman Sea and upper Gulf of Thailand should remain ashore.

Forecast from 6am August 13 to 6am August 14

Bangkok and surrounding provinces

  • Thunderstorms are forecast across 60% of the area, with isolated heavy rain.
  • Minimum temperature: 25–27°C
  • Maximum temperature: 33–35°C
  • South-westerly winds: 10–25 kilometres per hour

North

  • Thunderstorms are expected across 60% of the region, with isolated heavy rain in Mae Hong Son, Chiang Rai, Phayao, Nan and Tak.
  • Minimum temperature: 23–27°C
  • Maximum temperature: 32–35°C
  • South-westerly winds: 10–20km/h

Northeast

  • Thunderstorms are forecast across 60% of the region, with isolated heavy rain in Bueng Kan, Sakon Nakhon and Nakhon Phanom.
  • Minimum temperature: 23–26°C
  • Maximum temperature: 33–35°C
  • South-westerly winds: 10–20km/h

Central region

  • Thunderstorms are expected across 40% of the region, with isolated heavy rain in Uthai Thani, Saraburi and Kanchanaburi.
  • Minimum temperature: 23–26°C
  • Maximum temperature: 32–35°C
  • South-westerly winds: 10–25km/h

East

  • Thunderstorms are forecast across 60% of the region, with isolated heavy rain in Nakhon Nayok, Chachoengsao, Chanthaburi and Trat.
  • Minimum temperature: 24–28°C
  • Maximum temperature: 32–35°C
  • South-westerly winds: 20–40km/h
  • Waves: 2–3 metres, rising above three metres during thunderstorms

South, east coast

  • Thunderstorms are expected across 40% of the region, mainly in Phetchaburi, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala and Narathiwat.
  • Minimum temperature: 23–26°C
  • Maximum temperature: 33–36°C
  • South-westerly winds: 20–35km/h
  • Waves: 1–2 metres, rising above two metres offshore and during thunderstorms

South, west coast

  • Thunderstorms are forecast across 60% of the region, mainly in Phang Nga, Phuket, Krabi, Trang and Satun.
  • Minimum temperature: 24–27°C
  • Maximum temperature: 31–35°C
  • From Phang Nga northwards: south-westerly winds of 20–40km/h, with waves of 2–3 metres and above three metres during thunderstorms
  • From Phuket southwards: south-westerly winds of 20–35km/h, with waves around two metres and above two metres during thunderstorms