Air travellers using the three main airports are advised to leave home early during Songkran because road traffic will be heavy and passenger queues long at airports.
Pol Col Cherngron Rimpadee, spokesman for the Immigration Bureau, advised air travellers to plan on arriving at least three hours before departure at Suvarnabhumi, Don Mueang and Phuket airports from April 11-17.
The official Songkran holidays start on April 12 and end on April 17. The immigration office expects air many travellers to leave for holidays overseas a day earlier.
At Suvarnabhumi airport the number of outbound passengers is expected to rise by 30% from an average 120,000 to 160,000 a day from April 11, with similar rises at Don Mueang and Phuket.
Immigration will be fully staffed at the airports but long queues are expected, meaning passengers could have to wait at least an hour to clear passport control, Pol Col Cherngron warned.