The temperature on top of Doi Inthanon mountain plunged three degrees to 6 degrees Celcius early on Tuesday, the Doi Inthanon park chief said.
On Monday the temperature at the top of the popular tourist attraction was 9C, but it was recorded at 6C on Tuesday morning, said Rung Hiranwong, chief of the Doi Inthanon National Park in Chiang Mai's Jom Thong district.
He said the temperature at the Kiew Mae Pan viewpoint was recorded at 9C and at the Doi Inthanon Park office at 14C.
On Monday, 2,458 tourists visited the park, he said.
Frozen dew is expected on the mountaintop soon, he said.