Thai Meteorological Department Issues Heavy Rain and Storm Warning for 39 Provinces

On August 11, 2026, the Thai Meteorological Department (TMD) issued a weather alert for 39 provinces, forecasting heavy rain covering 70% of these areas. This weather pattern is driven by a monsoon trough extending across the upper North into low-pressure zones in Laos and Vietnam, combined with a relatively strong southwest monsoon over the Andaman Sea and the Gulf of Thailand.

Residents and travelers in affected regions, particularly those near foothills or low-lying areas, are advised to remain vigilant against potential flash floods and forest runoff. The TMD has also reported rough sea conditions, with waves in the upper Andaman Sea and upper Gulf of Thailand reaching heights of 2 to 3 meters, and exceeding 3 meters in areas experiencing thunderstorms.

For those currently in Thailand, the TMD recommends that small boats in the upper Andaman and Gulf regions refrain from leaving the shore. Mariners are urged to exercise extreme caution and avoid navigating through thunderstorm zones. While the forecast covers the 24-hour period ending at 6:00 AM on August 12, 2026, the duration of these conditions beyond this window remains to be confirmed. Travelers should monitor local updates regularly, as weather conditions can change rapidly during the monsoon season.