The tourist destination of Doi Inthanon in Chiang Mai was covered in frost Wednesday morning as the mercury dropped to minus 1 Celsius degree.
Kritsayam Kongsatree, chief of the Doi Inthanon National Park in Chiang Mai's Jom Thong district, said it was the first time this winter that the temperature had fallen below freezing.
He added that the cold had caused frost to form on the grass and leaves on the mountaintop, much to the delight of tourists to the area.
The park chief said the temperature at the Kiew Mae Pan viewpoint dropped to 1C while the temperature at the park office halfway up the mountain was about 8C.
The sky was clear Wednesday morning so tourists were treated to a sea of mist, Kritsayam added.
He advised tourists suffering from asthma to avoid trekking around Kiew Mae Pan as the cold and humidity could worsen their condition.