The New Year holiday is expected to see 33,400 Thais travelling overseas every day, increasing from an average of 28,000, mainly driven by pent-up demand from years of the pandemic, says the Tourism Authority of Thailand (TAT).
TAT governor Yuthasak Supasorn said the number of Thai travellers was surging as many popular destinations have reopened with no restrictions.
Meanwhile, weaker foreign currencies against the baht were also helping the growing outbound market, he said.
The top destinations for Thai travellers during the New Year holiday are Japan, South Korea, Vietnam, Singapore, and Laos.
The increasing number of flights to those destinations also helped expand the outbound market this month.
The majority of Thais who can afford outbound trips are middle- to high-income earners, who were unable to travel during the pandemic.
"The outbound market in December, particularly during the New Year holiday, saw the highest numbers in three years. This could affect domestic tourism to some extent as people pivot their spending to outbound destinations," said Mr Yuthasak.
From October to November, an average of 28,000 Thai travellers took outbound flights each day.
The number increased slightly to 28,800 per day between Dec 1-20, while the peak period is predicted for Dec 21-31, with 33,400 travellers per day, according to the TAT.
He said Thai tourists have booked more hotels in Asia this month, according to a study by booking.com, an online travel agent.
Santisuk Klongchaiya, chief executive of Thai AirAsia (TAA), said as more flights to Japan are added, average airfares on its route to Fukuoka had dropped slightly to 11,000-13,000 baht.
He said the average load factor to Japan had surged to 90% this month as the airline's Airbus A321neo planes have capacity of more than 230 seats.
Thai AirAsia X -- the long-haul carrier for the same group -- reported a high load factor of 88% for December as it expanded to Japan's key airports in Tokyo, Osaka and Sapporo.
However, the airline's limited fleet of five jets means the number of flights has yet to match pre-pandemic schedules.
For instance, the number of flights from Bangkok to Seoul is 10 per week, down from 21 flights per week, while service from Bangkok to Tokyo is nine flights per week, down from 21 flights before the pandemic.