The peak of Mau Son Mount at the height of 1,180 m above sea level in Lang Son Province on Tuesday morning.

As there were small rains when the temperatures fell, water froze and formed white icy cover on trees.

The National Center for Hydro-Meteorological Forecasting reports that temperatures at the Mau Son peak dipped to minus 1 degree Celsius on Tuesday morning but the actual outdoor temperature was minus 3 degrees Celsius, marking the peak the coldest place in northern Vietnam.

Mau Son peak is home to several tourist facilities and since Monday afternoon when the ice started to form, people in Lang Son and elsewhere have flocked to the peak to see frost, which is quite rare in a tropical country.

By Tuesday morning, all vehicles left outdoors without cover could not function due to the frost.

The road to Mau Son peak is slippery with ice but many still try to reach the peak to admire the rare sight of the year.

The wind blows very strongly on Yen Tu and therefore the ice is not as thick as in Mau Son.

Lying 1,068 m above sea level, Yen Tu Peak saw its temperature drop to 0 degee Celsius on Tuesday morning.

Fog and small rain froze on plants.

Most places of northern Vietnam saw temperatures below 10 degrees Tuesday morning. Other places with low temperatures include Vinh Phuc's Tam Dao at 1 degree, Ha Giang's Dong Van at 2 degrees, and Lao Cai's Sa Pa at 3 degrees.

Ice and frost have appeared on the peak of Phia Oac in Cao Bang since Monday afternoon.

The ongoing cold wave, where average daytime temperatures stay below 15 degrees in the plains, would last until Jan. 25 for northern and north-central Vietnam, according to the National Center for Hydro-Meteorological Forecasting.