First hoar frost of 2025 appears on Doi Inthanon on Monday

The first hoar frost of the 2025 winter season was reported near the summit of Doi Inthanon in Chiang Mai early on Monday morning, according to Doi Inthanon National Park officials.

The park said the frost formed around kilometre marker 46 on the road leading to the peak, delighting tourists who had flocked to the mountaintop to enjoy the chilly weather and wait for the first rays of sunlight.

The frost — a deposit of feathery, needle-like or crystalline ice — appeared on exposed grass and leaves.

Park officials said the temperature at the summit was measured at 5 degrees Celsius, while the mercury at the Kew Mae Pan Nature Trail dropped to 4C, and the temperature at the park office stood at 8C.

Large numbers of visitors gathered at Kew Mae Pan to wait for the first sunlight of the day.

The park added that over the weekend, more than 4,000 tourists visited the area.

Hoar frost typically occurs in Thailand between November and February on the summits of Doi Inthanon, Doi Chiang Dao, Doi Ang Khang, Doi Phahom Pok, Phu Ruea and Phu Luang.

Hoar frost forms through a process known as deposition (or desublimation), where water vapour transforms directly into ice without passing through the liquid stage.