Effective midnight last night (Friday April 03 2020) and for 72 hours Thailand has announced that they are suspending all incoming passenger flights.
Anyone who arrives on a flight that took off before the ban came into force will be allowed to arrive, but will be quarantined for 14 days after arriving in Thailand.
They are also reporting that Phuket Airport will close for 3 weeks, from April 10 to April 30, but his is not yet confirmed.