The Thai meteorological service warns of a wet and turbulent week from May 16 to 22, 2026. The southwest monsoon is increasing in strength and bringing a lot of moist air over Thailand. As a result, severe thunderstorms are developing in several regions, with locally heavy to very heavy rain.
From May 17, an active low-pressure system over Myanmar and western Thailand will also play a role. This increases the chance of prolonged rain, particularly in the north, west, and south. For tourists and expats, this means being extra careful when traveling, taking boat trips, and staying in hilly areas.
Monsoon causes heavy showers in large parts of Thailand
The heaviest rain is expected in northern Thailand. There, showers could become locally very intense between May 18 and 22. Scattered to fairly widespread thunderstorms are also expected in the northeast, the center, the east, and Bangkok.
In the central part of Thailand, the west in particular may experience very heavy rain between May 18 and 21. In Bangkok and the surrounding area, the weather will remain changeable throughout the period, with a chance of locally heavy showers from May 18 to 21. Temperatures will remain high, with highs of around 33 to 36 degrees.
Risk of sudden floods and waterlogging
Residents and travelers in hilly areas, along waterways, and in low-lying zones should be alert. Due to persistent rain, water can accumulate rapidly. This increases the risk of flash floods, mudslides, and local water nuisance.
Caution is advised, especially in the north and south. Roads may become temporarily impassable, and small rivers or drainage canals can fill up quickly. Anyone traveling through Thailand in the coming days would do well to follow local warnings and plan flexibly.
Rough seas near the Andaman Sea and Gulf of Thailand
The situation at sea is risky. Waves of 2 to 3 meters are expected in the Upper Andaman Sea. During thunderstorms, these can exceed 3 meters. Small boats in the northern part of the Andaman Sea must remain ashore from May 16 to May 22.
The sea can also become rough in the Gulf of Thailand. Waves there are around 2 meters, with higher waves during thunderstorms. All vessels are advised to sail cautiously and avoid thunderstorm areas. This also applies to tourist boat routes around islands and coastal towns.
Rain forecast by region
In the north, scattered thunderstorms with locally heavy rain will occur on May 16 and 17. From May 18 to 22, the showers will increase, and locally very heavy rain is possible. Minimum temperatures will range between 22 and 27 degrees, and maximum temperatures between 30 and 37 degrees.
In the northeast, scattered to fairly widespread rain is expected between May 17 and 22, with heavy showers, and locally very heavy rain from May 19 to 21. In the east, it will remain showery throughout the entire period. There, the sea may become rougher from May 18, with waves around 2 meters and higher waves during thunderstorms.
Southern Thailand gets rain and dangerous waves
Along the east coast of Southern Thailand, more showers will fall from May 18 to 22, with locally very heavy rain from May 19 to 21. From Surat Thani northwards, the wind may pick up and waves at sea could reach around 2 meters. Higher waves are expected during thunderstorms.
Along the west coast, including Phangnga, Phuket, and Krabi, the Andaman Sea remains rough. Locally very heavy rain is possible between May 18 and 21. North of Phuket, waves can reach 2 to 3 meters, exceeding 3 meters during thunderstorms. Extra caution is required for beachgoers, divers, and boat travelers.
The coming week in Thailand will be significantly wetter and more turbulent. Heavy rain, rapidly rising water levels, and rough seas, in particular, pose risks. Anyone traveling, sailing, or staying in vulnerable areas would be wise to monitor local weather warnings daily.
Source: Thai Meteorological Department
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