Thailand: Adverse weather forecast across much of the country through at least Dec. 25

Adverse weather is forecast across much of the country through at least Dec. 25. As of Dec. 19, the Thai Meteorological Department has issued a weather warning for cold temperatures, heavy rainfall in southern regions, and rough seas in the Gulf of Thailand. A high-pressure system is forecast to bring a drop in temperatures and strong winds across central, eastern, and northern regions Dec. 20-25. Meanwhile, a strengthening of the northeast monsoon and an active low-pressure system will combine to bring heavy rainfall to southern regions Dec. 22-25. Flooding is possible in low-lying parts of the affected regions, as well as landslides on unstable slopes. Rough seas are also expected in the Gulf of Thailand, with waves of up to 4 meters (13 feet). Waves of over 2 meters (7 feet) are also possible in the Andaman Sea. People along the southeast coast have been advised to remain alert for storm surges and all ships are advised to proceed with caution. The department recommends small vessels in the Gulf of Thailand remain ashore Dec. 22-25. Officials could update and extend the coverage of the relevant weather alerts over the coming days.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil. Disruptions to electricity and telecommunications services are possible where significant flooding, landslides, or strong winds impact utility networks.

Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather could also trigger intermittent flight delays and cancellations at airports across the affected regions, though these are unlikely to be severe or prolonged. Authorities may temporarily suspend port operations or close beach fronts in the Gulf of Thailand if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track inundation. Localized business disruptions may occur in low-lying areas.

Flooding could heighten the threat of disease outbreaks. Backflow from drains mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become a breeding ground for mosquitoes and bacteria, increasing the incidence of insect- and water-borne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.