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Thailand Weather Forecast: June 3, 2026
A strong southwest monsoon is driving unsettled weather across all regions of Thailand on June 3, 2026, with the Thai Meteorological Department (TMD) forecasting thunderstorms everywhere from the far north to the southern peninsula. The forecast covers the 24-hour period from 6am June 3 to 6am June 4. Rough seas, heavy rain, and flash flood risks make this a day to plan carefully, especially if you are based on or traveling to coastal areas.
What's Driving the Weather
The main weather system is a moderately strong southwest monsoon sitting over the Andaman Sea, the Gulf of Thailand, and mainland Thailand. This is typical for early June, but the intensity is enough to push thunderstorms into every region of the country simultaneously.
Koh Lanta and the Andaman Sea
Koh Lanta sits on the Andaman Sea, which is directly in the path of this monsoon system. Waves are forecast at 2 to 3 metres, rising above 3 metres in areas hit by thunderstorms. The TMD is advising small boats to stay ashore in the Andaman Sea and upper Gulf of Thailand. Boat trips, island transfers, snorkelling, and diving are likely to be unsafe or cancelled on this day.
Southern Thailand
Both coasts of the south are affected, with 60% thunderstorm coverage forecast across the region.
West coast (Andaman side): Rough sea conditions as described above, with small boat operators specifically told to remain ashore.
East coast (Gulf side): Provinces including Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, and Songkhla are all in the forecast area. Winds range from 20 to 40 km/h north of Surat Thani, and 20 to 35 km/h from Nakhon Si Thammarat southward. Waves on the Gulf east coast are forecast at 1 to 2 metres, rising higher offshore and during storms. Koh Samui sits within the Surat Thani zone.
Temperatures across southern Thailand will range from around 23°C to 35°C.
Eastern Thailand
Eastern provinces including Chon Buri (Pattaya), Rayong, Chanthaburi, and Trat face some of the harshest conditions in the forecast. Storm coverage hits 60% of the region, with heavy to very heavy rainfall expected. Winds reach 20 to 40 km/h and sea waves run 2 to 3 metres, exceeding 3 metres during storms. Koh Chang falls within the Trat zone. Temperatures will be 24°C to 36°C.
Central and Northern Thailand
Central Thailand, including Kanchanaburi and Ratchaburi, has 40% thunderstorm coverage with temperatures between 23°C and 37°C and southwest winds at 10 to 20 km/h.
Northern Thailand sees 40% coverage as well, with affected provinces including Mae Hong Son and Tak. Temperatures range from 22°C to 38°C, and winds stay at 10 to 20 km/h. Conditions here are less intense compared to coastal areas, but disruption is still likely.
Northeast Thailand also has 40% thunderstorm coverage across 11 provinces including Nakhon Ratchasima and Ubon Ratchathani, with temperatures from 23°C to 37°C.
Safety Advice from the TMD
The TMD is urging people in affected areas to prepare for standing water, flash flooding, and runoff, particularly in low-lying areas and near waterways. Boat operators are advised to avoid sailing through stormy conditions. Road conditions may also deteriorate due to heavy runoff, so allow extra time if you are driving and avoid flood-prone roads where possible.
Information sourced from The Thaiger.