Tropical storm Pabuk is expected to land around 7pm. Local time Friday (5 pm ET) near the Chumphon Archipelago, on the eastern border of the Thai provinces Surat Thani and Nakhon Si Thammarat, but heavy rains have already started.
Tourist hotspots in the Gulf of Thailand, including Koh Samui, Koh The islands of Phangan and Koh Tao as well as islands in the Andaman Sea such as Phuket and Koh Phi Phi – made famous by the movie "The Beach" – are likely to be affected by the storm.
"We are still working on the number of evacuees – I can say that several thousand people are from more than 16 provinces," government spokesman Putthipong Punnakanta told CNN over the phone.
"It's high season, there are a lot of foreign tourists in popular destinations, we've been informing them two days in advance, I'd say most of them left the islands and came to the mainland."
Phuwieng Prakhammintara The director-general of the Thai Department of Meteorology told CNN that the storm could cause waves up to seven meters high, but the waves could reach 3 to 5 meters.
Coastal schools are closed and Thai forces stand ready for Pabuk's arrival.
Bangkok Airways announced Friday that all flights to and from Koh Samui were canceled "for safety reasons". Concerned passengers can rebook their flights without paying any fees or charges, the airline said.
After the storm has crossed Chumphon Archipelago, if the current lane holds, the storm will land a second time off Surat Thani Province.  Pabuk will then move relatively quickly across the Malay Peninsula towards the Andaman Sea, but not before large amounts of rain are sunk in the region.
The storm is expected to bring strong winds, high waves and surf with flooding. While the wind, surf and surf will be particularly dangerous in an area where such storms are not visible, the rain and flood potential is the greatest danger.
In areas in the southernmost part of Thailand, there can be well over 250 mm of precipitation. There is also the possibility of mudslides from the Phuket Mountains on the western side of the peninsula.
It is extremely unusual for tropical storms and typhoons to land in Thailand. The last time a tropical storm landed in Thailand was in 1962, when tropical storm Harriet hit 12 provinces and claimed 900 lives. The only typhoon ever to land in the Southeast Asian nation was Typhoon Gay in 1989.
The worst affected province is Nakhon Si Thammarat, where Harriet met
Towards the Bay of Bengal, it could become a problem for the coasts of Myanmar, Bangladesh or India next week.
CNN's Kocha Olarn reported from Bangkok while Laura Smith-Spark from London and Euan McKirdy from Hong Kong wrote. CNN's Michael Guy and Yuli Yang contributed to the report.