Thailand Issues 11th Heavy Rain Alert; Flash Floods Possible
Thailand's meteorological department issued its 11th heavy rain alert, with 47 provinces facing risks of flash floods and dangerous sea conditions through September 20 as monsoon systems intensify across the country.
On September 20, 2026, the Thai Meteorological Department issued its 11th weather alert concerning heavy to very heavy rainfall across Thailand and strong winds in the Andaman Sea, with effects lasting through September 20, 2026. The alert notes that a high-pressure system and cold air mass from China is covering the upper northern and upper northeastern regions, while a monsoon trough crosses the lower central region, eastern region, and upper southern region. The southwest monsoon is strengthening over the Andaman Sea, southern Thailand, and the Gulf of Thailand.
The meteorological office identified 47 provinces experiencing heavy rain. Residents throughout Thailand are warned to stay vigilant against the dangers of heavy rainfall and accumulated precipitation, which may trigger flash floods and flash flooding, particularly in foothill areas near waterways and low-lying zones. Travelers should avoid routes with recurring flood problems, especially in low-lying areas prone to short-term inundation.
Waves in the upper Andaman Sea are moderately strong, with heights of 2-3 meters; thunderstorm areas may see waves exceeding 3 meters. Fishermen in the Gulf of Thailand and Andaman Sea are advised to navigate with caution and avoid thunderstorm zones. Small boats in the upper Andaman Sea are recommended to remain ashore for another day.
The public is urged to plan their daily activities and travel carefully during this period. Updates are available on the Thai Meteorological Department website at http://www.tmd.go.th or by calling 0-2399-4012-13 and 1182, available 24 hours a day. The next alert will be issued on September 20, 2026, at 5:00 p.m.
