The popular winter tourist destination Doi Inthanon in Chiang Mai was blanketed with white frost on Wednesday morning when the mercury dropped to minus 2 degrees Celsius.
Rung Hiranwong, chef of the Doi Inthanon National Park in Jomthong district, said it was the first time this year that the temperature dropped below zero.
He said white frost was seen on grass leaves and tourist vehicles early in the morning.
The temperature at the Kiew Mae Pan viewing spot for watching the sea of mist was 3C, while the Doi Inthanon park office saw a temperature of 9C.
Rung said about 4,000 tourists were visiting the mountaintop each day now.