Thailand faces heavier rain as monsoon system builds

Thailand is set for more rain as a moderate southwest monsoon combines with a low-pressure cell over upper Vietnam, bringing thunderstorms and isolated heavy downpours to 46 provinces, including Bangkok and surrounding areas.

The Thai Meteorological Department (TMD) warned that the country would see more unsettled weather over the next 24 hours, with heavy rain expected in parts of the Northeast, Central region, East, western coast of the South, and Greater Bangkok.

People in affected areas have been urged to take precautions against thunderstorms, heavy rain and accumulated rainfall, which could increase the risk of local flooding and other weather-related hazards.

The current conditions are being driven by a moderate southwest monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand, together with a low-pressure area over upper Vietnam.

Marine conditions are also becoming more challenging. Waves in the upper Andaman Sea are forecast to reach around two metres, while the lower Andaman Sea and upper Gulf of Thailand will see waves of one to two metres. In thunderstorm areas, waves may rise above two metres.

The TMD advised boats in the Andaman Sea and Gulf of Thailand to proceed with caution and avoid sailing in areas experiencing thunderstorms.

Heavier rain forecast from June 28 to July 3

A fresh round of rain is expected to affect Thailand from June 28 to July 3, when rainfall will increase across the country, with isolated heavy to very heavy rain forecast in some areas.

The East and the western coast of the South are expected to be particularly vulnerable during this period.

The heavier spell will be driven by a monsoon trough lying across the North and upper Northeast, while the southwest monsoon over the Andaman Sea, Thailand and the Gulf of Thailand is expected to strengthen.

During this period, waves in the upper Andaman Sea are forecast to become rather strong, reaching two to three metres. In thunderstorm areas, waves could rise above three metres.

Regional forecast from 6am on June 27 to 6am on June 28

North
Thunderstorms are forecast in 40% of the region, mainly in Mae Hong Son, Chiang Mai, Phayao, Nan, Tak, Phitsanulok and Phetchabun. Temperatures will range from 23-27°C in the morning to 34-37°C during the day. Southwesterly winds will blow at 10-20 kilometres per hour.

Northeast
Thunderstorms are expected in 40% of the region, with isolated heavy rain in Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Amnat Charoen and Ubon Ratchathani. Temperatures will range from 24-25°C to highs of 35-37°C. Southwesterly winds will blow at 10-20 kilometres per hour.

Central region
Thunderstorms are forecast in 60% of the region, with isolated heavy rain in Kanchanaburi, Ratchaburi, Suphan Buri, Saraburi, Phra Nakhon Si Ayutthaya, Nakhon Pathom, Samut Sakhon and Samut Songkhram. Temperatures will range from 24-25°C to 35-37°C. Southwesterly winds will blow at 10-20 kilometres per hour.

East
Thunderstorms are expected in 60% of the region, with isolated heavy rain in Nakhon Nayok, Prachin Buri, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat. Temperatures will range from 24-27°C to 33-37°C. Southwesterly winds will blow at 15-35 kilometres per hour. Waves will be one to two metres high, rising above two metres in thunderstorm areas.

South, east coast
Thunderstorms are forecast in 40% of the region, mainly in Phetchaburi, Chumphon, Surat Thani, Nakhon Si Thammarat, Songkhla, Yala and Narathiwat. Temperatures will range from 23-26°C to 33-36°C.

From Surat Thani northwards, southwesterly winds will blow at 15-35 kilometres per hour. Waves will be around one metre high, rising to one to two metres offshore and above two metres in thunderstorm areas.

From Nakhon Si Thammarat southwards, southwesterly winds will blow at 15-30 kilometres per hour. Waves will be around one metre high, rising above two metres in thunderstorm areas.

South, west coast
Thunderstorms are forecast in 70% of the region, with isolated heavy rain in Ranong, Phang Nga, Phuket and Krabi. Temperatures will range from 24-25°C to 31-35°C.

From Phang Nga northwards, southwesterly winds will blow at 20-35 kilometres per hour. Waves will be around two metres high, rising above two metres in thunderstorm areas.

From Phuket southwards, southwesterly winds will blow at 15-35 kilometres per hour. Waves will be one to two metres high, rising above two metres in thunderstorm areas.

Bangkok and surrounding provinces
Thunderstorms are expected in 60% of the area, with isolated heavy rain. Temperatures will range from 24-26°C to 34-36°C. Southwesterly winds will blow at 10-20 kilometres per hour.