This endemic natural phenomenon in the highland occurred one day ahead of the arrival of winter (November 7), according to the lunar calendar.
According to meteorologists, the ongoing cold and dry air sweeping across the Hoang Lien Son mountain range was in full swing overnight on November 5.
At night, the sky was clear and cloudy that hastened the process of heat radiation on the ground. As a result, the temperature on Fansipan Mt. peak to decrease sharply, causing hoarfrost to set in.
As winter is drawing near, thin layers of hoarfrost were melted as soon as the sun rose. However, early ground hoarfrost as seen on Fansipan Mt. peak on November 6 was described as rare this year.