Floodwaters shut down Nakhon Si Thammarat International Airport on Thursday.
Airports Department chief Darun Saengchai told reporters via Line app messages that the airport had to be closed at 1.50am and would remained so until midnight.
Floodwaters were being drained off as quickly as possible and his department was monitoring the situation closely to determine when the airport could reopen, he said.
Airport officials separately announced they would evaluate the situation day by day before deciding whether the facility would reopen.
Travellers are advised to contact their airlines regarding flight cancellations or postponements. Nok Air is at 083-5408538-9, Air Asia at 075-450505, and Thai Lion Air at 02-529-9999.