Bangkok's Suvarnabhumi airport's total passenger numbers decreased 2.6% to 4.49 million in August, compared with the same month last year.
The airport's international passenger numbers rose by 4.9% to 3.69 million, while its domestic passenger numbers dropped by nearly 27% to 803,000, says Airports of Thailand (AOT).
Total aircraft movements at the airport fell by 4% to 25,600.
The total amount of cargo handled by the airport went down by 4.7% to 103,000t.
Apart from Bangkok's Suvarnabhumi and Don Mueang airports, AOT also operates airports in Chiang Mai, Chiang Rai, Phuket and Hat Yai.
The total number of passengers at all six airports grew to 18% to 7.68 million in August, compared with the same month last year. The number of international passengers increased by 19% to 4.82 million, while domestic passenger numbers rose by 16% to 2.86 million.
Total cargo volumes at the six airports decreased by 3.5% to 110,000t, while total aircraft movements increased 19% to 49,300.