Tens of thousands of tourists have fled the Thai resort islands of Koh Phangan and Koh Tao in a mass exodus ahead of Tropical Storm Pabuk which is set to bring heavy rains, wind and seven-metre (22-foot) waves, officials said Thursday.

The islands, hugely popular with holiday-makers especially during the peak Christmas and New Year season, have emptied out since Wednesday as tourists packed onto ferries bound for the southern Thai mainland, with swimming banned and boats set to suspend services.

Pabuk, Thailand’s first tropical storm in the area outside of the monsoon season for around 30 years, is poised to batter Koh Phangan and Koh Tao as well as Koh Samui on Friday night, before cutting into the mainland.