Thailand is bracing for significant rainfall on September 19, 2026, with the Thai Meteorological Department issuing forecasts for heavy rain in 49 provinces. The capital city, Bangkok, is expected to experience widespread showers and localized downpours. Residents are advised to exercise caution due to the potential for flash floods, overflowing waterways, and landslides, particularly in areas near foothills and low-lying regions.
National Weather Overview and Forecast
The current weather pattern is influenced by a monsoon trough extending across the lower central, upper southern, and eastern parts of Thailand. Concurrently, a strong southwest monsoon is active over the Andaman Sea, the entire country, and the Gulf of Thailand. This combination is conducive to widespread rainfall, with the possibility of isolated very heavy downpours, especially along the west coast of the southern region.
Temperatures across the country are expected to range between 23°C and 35°C, depending on the specific region and time of day. Winds will vary, generally blowing from the south or southeast, with speeds ranging from 10 to 40 km/h. Wave heights in the seas are also expected to increase, particularly in areas experiencing thunderstorms.
Regional Forecasts
Bangkok and Vicinity
The capital is forecast to experience fairly widespread thundershowers and isolated heavy rain. Temperatures in Bangkok will range from a minimum of 24-26°C to a maximum of 31-34°C. Southerly winds are predicted at 10-25 km/h.
Northern Thailand
Scattered thundershowers and isolated heavy rain are anticipated in several northern provinces, including Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Tak, Sukhothai, Kamphaeng Phet, Phichit, Uttaradit, Phitsanulok, and Phetchabun. Minimum temperatures are expected to be between 23-25°C, with highs reaching 31-35°C. Easterly winds of 10-20 km/h are forecast.
Northeastern Thailand
Provinces such as Nakhon Ratchasima and Buri Ram in the Northeast can expect scattered thundershowers and isolated heavy rain. The temperature range is predicted to be 23-24°C for lows and 32-34°C for highs. Easterly winds will be around 10-20 km/h.
Central Thailand
A significant portion of the central region will see fairly widespread thundershowers and isolated heavy rain. Affected provinces include Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram, and Samut Sakhon. Minimum temperatures will be between 23-25°C, with maximum temperatures ranging from 32-35°C. Southeasterly winds are expected at 10-25 km/h.
Eastern Thailand
Fairly widespread thundershowers and isolated heavy rain are forecast for the eastern provinces of Chachoengsao, Chonburi, Rayong, Nakhon Nayok, Prachinburi, Sa Kaeo, Chanthaburi, and Trat. Temperatures will range from 23-25°C at night to 30-35°C during the day. Southwesterly winds are predicted at 20-35 km/h, with wave heights around 2 meters, potentially exceeding 2 meters in thundershower areas.
Southern Thailand (East Coast)
Scattered thundershowers and isolated heavy rain are expected along the east coast of the South, affecting Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala, and Narathiwat. Minimum temperatures will be between 23-26°C, and maximums between 30-34°C. Wind speeds will vary by location, with wave heights generally between 1 to 2 meters, and higher in thundershower zones.
Southern Thailand (West Coast)
The west coast of the South faces the highest risk, with fairly widespread thundershowers and isolated heavy rain predicted in Phuket, Krabi, Trang, and Satun. Notably, Ranong and Phang Nga provinces could experience isolated very heavy rain. Minimum temperatures are expected to be 23-25°C, with highs between 28-31°C. Wave heights are forecast to be significant, ranging from 2-3 meters and potentially exceeding 3 meters in areas with thundershowers.
Advisory and Warnings
The Thai Meteorological Department strongly advises the public to be aware of the potential hazards associated with the heavy to very heavy rainfall. Accumulations of rain could lead to flash floods, cause rivers and canals to overflow, and trigger landslides. These risks are particularly elevated in areas situated near mountain foothills and in low-lying flood-prone zones. Residents in these areas are urged to stay informed and take necessary precautions to ensure their safety.
