Because of the ongoing violence in the deep south, all major Western governments are currently advising people not to travel to or through Pattani, Yala and Narathiwat provinces unless essential, and nearly all are advising against travel to Songkhla province too; following on from this, insurance companies are refusing to cover travel in the affected areas. The four provinces encompass the city and transport hub of Hat Yai and several of the main border crossings to Malaysia: by rail from Hat Yai (and Bangkok) to Butterworth via Padang Besar and to Sungai Kolok; and by road from Hat Yai via Sadao, from Yala via Betong, and down the east coast to Kota Bharu.
The routes to Sungai Kolok, Betong and Kota Bharu pass through particularly volatile territory, with martial law declared in Pattani, Yala and Narathiwat provinces; however, martial law is only in effect in certain districts of Songkhla province, and not in Hat Yai itself.
The provinces of Trang and Satun are not affected, and it’s still perfectly possible to continue overland to Malaysia via Satun: by a/c minibus from nearby Ban Khuan to Kangar, or by ferry from Thammalang to Kuala Perlis or the Malaysian island of Langkawi; or by boat from Ko Lipe to Langkawi. For up-to-the-minute advice, consult your government travel advisory.