Thailand Braces for Heavy Rain and Flash Flood Risk

The Thai Meteorological Department has forecast lighter rain across Thailand from 16-19 July 2026, before showers and heavy rain return on 20-21 July, raising concerns over flash floods, runoff and overflowing rivers. The agency said the North and the western part of the Central region are the areas that need the closest watch.

From 16-19 July, rainfall will ease nationwide, although some areas in the North and upper Northeast will still see heavy rain as a low-pressure area lingers over upper Vietnam. The southwest monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand will weaken during this period.

From 20-21 July, rain is expected to increase again, with heavy showers in some areas, especially in the North and the western part of the Central region, as a low-pressure cell moves over Laos and upper Vietnam and the southwest monsoon strengthens. The department warned that accumulated rainfall could trigger flash floods, forest runoff and overflowing waterways, especially in foothill areas near channels and low-lying land.

Wave conditions in the Andaman Sea and the Gulf of Thailand are expected to remain moderate, with upper Andaman waves around 2 metres and more than 2 metres in thundershowers. Lower Andaman waters and the upper Gulf are forecast at 1-2 metres, rising above 2 metres in stormy areas.

In the North, thunderstorms are likely over 30-40% of the area from 15-19 July, rising to 40-60% on 20-21 July, with isolated heavy rain. Temperatures will range from 23-27°C to 29-35°C, with southwest winds of 10-20 km/h.

In Bangkok and surrounding provinces, thunderstorms are expected over 30-40% of the area on 16-17 July and again on 21 July, with rain easing to 20-30% on 18-20 July. Temperatures will range from 26-28°C to 32-36°C.