The Thai Meteorological Department (TMD) has issued a forecast indicating the occurrence of summer thunderstorms across several provinces in upper Thailand from May 9 to May 12, 2023.
The affected areas include Bangkok and its surrounding regions, with the first outbreaks expected in the Northeast before expanding to other parts of the country.

The forecast predicts thunderstorms accompanied by gusty winds, hail, and heavy rainfall, along with lightning strikes.
These weather conditions are attributed to a moderate high-pressure system extending from China into Vietnam and the South China Sea.
Additionally, southerly and southeasterly winds are expected to carry moisture from the South China Sea and the Gulf of Thailand into upper Thailand, which is currently experiencing hot to very hot weather.

The public in the affected regions is advised to exercise caution during thunderstorms due to the risk of strong winds, hail, and lightning.
Recommendations include avoiding outdoor activities when storms are imminent and staying away from large trees and unsecured billboards.
Residents are also cautioned about the potential for flash flooding and water accumulation, especially near waterways, foothills, and low-lying areas.
Farmers should implement protective measures for their crops to mitigate potential damage from adverse weather.

The forecast details the specific areas affected on each day:

May 9

Northeast: Loei, Nong Bua Lam Phu, Udon Thani, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Khon Kaen, Maha Sarakham, Kalasin, Mukdahan, Roi Et, Yasothon, Amnat Charoen, and Ubon Ratchathani.

May 10

North: Nan, Phrae, Uttaradit, Phichit, Phitsanulok, and Phetchabun.

Northeast: Loei, Nong Khai, Bueng Kan, Nong Bua Lam Phu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Kalasin, Khon Kaen, Mukdahan, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket, and Ubon Ratchathani.

Central: Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Ayutthaya, Suphan Buri, and Kanchanaburi, including Bangkok and its vicinity.

East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi, and Trat.

May 11

North: Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Phrae, Uttaradit, Sukhothai, Kamphaeng Phet, Phichit, Phitsanulok, Phetchabun, and Tak.

Northeast: Loei, Nong Bua Lam Phu, Chaiyaphum, Khon Kaen, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket, and Ubon Ratchathani.

Central: Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, and Samut Songkhram, including Bangkok and its vicinity.

East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi, and Trat.

South: Phetchaburi and Prachuap Khiri Khan.

May 12

North: Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phrae, Uttaradit, Tak, Sukhothai, Kamphaeng Phet, Phichit, Phitsanulok, and Phetchabun.

Northeast: Chaiyaphum, Nakhon Ratchasima, Buri Ram, and Surin.

Central: Nakhon Sawan, Uthai Thani, Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Ayutthaya, Suphan Buri, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, and Samut Songkhram, including Bangkok and its vicinity.

East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi, and Trat.

South: Phetchaburi, Prachuap Khiri Khan, and Chumphon.

In addition to the thunderstorms, an intensifying southwesterly wind is anticipated over the Andaman Sea and southern Thailand, resulting in increased rainfall and isolated heavy showers across various provinces, including Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Ranong, Phang Nga, Phuket, Krabi, and Trang from May 10 to May 12.

Residents in the southern regions are advised to remain vigilant regarding the risks of heavy rainfall, which could lead to flash floods and overflow, particularly in areas near waterways, foothills, and low-lying areas.
Strong winds are anticipated to generate waves up to two meters high in the Andaman Sea, potentially exceeding this height in regions experiencing thundershowers.
The TMD has urged caution for all vessels to avoid navigating in stormy conditions.