Baby, it's cold outside!

The department's statement said the mercury would drop 1 to 3 degrees Celsius and warned of strong winds and high waves in the Gulf of Thailand.

The temperature in Bangkok fell to 14 degrees on Sunday night.

Chiang Mai weather bureau forecaster Pensiri Trisat predicted the North's cold snap would get colder, with the mercury falling 1 to 3 degrees by Thursday. That would bring the temperature in the hills down to between 1 and 7 degrees, and the plains hovering between 8 and 14 degrees Celsius, she said.

Loei province has been suffering an even deeper freeze: residents have been waking up to frost after the temperature crept below zero in some areas. Loei weather bureau chief Khampahn Butrarat said that the chill - caused by an area of high pressure from China - would deepen by 1 or 2 degrees in the next couple of days.

In Phetchabun, tourists are still pouring into Nam Nao National Park, braving frosts and temperatures of one degree Celsius, the lowest there in eight years.