Wasan Chanthep, assistant chief of Doi Inthanon National Park, said the lowest temperature was measured atop Doi Inthanon while it was higher, 12C, at the Kiew Mae Pan lookout point.
He said tourists staying nearby went to the mountaintop on Friday specifically to enjoy the low temperature.
The spot was also covered with thick fog but no rain, he added.
There has still been no frost recorded at Doi Inthanon this winter.