The cold has moved further inland, causing temperatures to drop to a low of four degrees C in mountainous areas and about 9 degrees C in the plain.
The temperature has also fallen by about 2-3 degrees C with light rain in the lower part of Cao Bằng province, according to a local official.
Local authorities have alerted residents about the bad weather conditions in order to protect human and animal health. Currently, frost has covered primeval forests and construction works on top of the Phia Oac mountain range, which is more than 1,900m above sea level in Cao Bằng province.
This is the first time this year frost has been seen in the area, with nighttime temperatures dropping to about minus 2 to minus 5 degrees C with light rain and strong winds.
