In August 2026, the
monsoon trough lay across the upper part of northern Thailand, Laos and upper
Vietnam for most of the month. At times, it shifted northward to lie across
Myanmar, Laos and upper Vietnam. As a result, rainfall over upper Thailand was
uneven in both amount and distribution, with most areas received below-normal
rainfall. However, upper Thailand experienced abundant rainfall at some
periods, particularly in the northern and northeastern regions, due to the
influence of the monsoon trough lay over the northern and upper northeastern Thailand
in some period. The monsoon trough extended into an active low-pressure cell
over the upper South China Sea and Hainan Island during 19-20
August. The low-pressure cell subsequently intensified into the tropical depression
on 21 August and developed into the tropical storm “NARRA (2619)” in on 22
August and remained nearly stationary over the Gulf of Tonkin before making
landfall in southern Guangdong Province, China, on 26 August. The precursor
systems of NARRA brought abundant rainfall in the northern and northeastern regions,
with fairly widespread rain and heavy to very heavy rainfall in many areas, resulted
in severe flooding and landslide in some places. In the southern region, the southwest
monsoon periodically strengthened over the Andaman Sea, Thailand and the Gulf
of Thailand, resulting in rainfall mainly along the west coast. Monthly rainfall was below normal in all regions the northern
part 3.9 mm (2%), northeastern part 17.7 mm (7%) central part 24.2 mm (13%),
eastern part 56.2 mm (20%), the southern part (east coast) 49.7 (39%) and
southern part (west coast) 182.0 mm (43%). The average total rainfall over
Thailand in this month was 17% lower than normal. Overall, the average
temperature across Thailand was 0.4 ˚C higher than normal. Further details are as follows:
Announcement Date 31 August 2026 16:39