Hoarfrost forms atan altitude of 3,000m and above after midnight, persisting until the earlymorning of the day, according to the observations of visitors.
Higher temperatures and the end of the rare weatherphenomenon are forecast for November 7.
Hoarfrost is dangerous as it can cause damage to crops andlivestock by inhibiting the growth and development of plants.
In the highlands of Lao Cai, the phenomenon often occursduring the winter months, especially in December, January and February./.