Frost blanketed the wooden platform surrounding the Fansipan monument and nearby plants at around 5 a.m. Saturday. The frost melted within 30 minutes as the sun rose. Standing at 3,147.3 meters (10,326 feet) above sea level, Fansipan is part of the Hoang Lien Son Mountain Range in Sa Pa, Lao Cai Province.

A thin ice layer covers the wooden floor atop Fansipan, Nov. 23, 2024.

The National Center for Hydro-Meteorological Forecasting explained that the frost formed due to cold air and dry northeastern winds, which caused temperatures to drop sharply overnight. Early Saturday, Sa Pa and other northeastern mountainous areas recorded temperatures of 10-11 degrees Celsius, while Hanoi registered 19 degrees.

Daytime temperatures rose to 25-28 degrees in northern Vietnam as the sun warmed the region, creating a large temperature gap between day and night. Humidity levels below 50% made the weather dry and crisp.

The north is expected to see intensified cold air in the coming days, with nighttime temperatures in mountainous areas forecast to drop to 11-12 degrees and plains ranging from 15-17 degrees.

AccuWeather predicts Hanoi’s temperatures will range from 15-20 degrees Celsius next week, while high-altitude locations like Sa Pa (above 1,500 meters) could face severe cold, dipping below 13 degrees.

According to meteorologists, temperatures on Fansipan's summit could fall to 0-3 degrees Celsius, as temperatures drop by 0.6 degrees for every 100-meter rise in altitude, increasing the likelihood of ice formation.

Frost forms when air temperatures fall below 4 degrees Celsius and surface temperatures near the ground approach 0 degrees, causing moisture in the air to condense into white, salt-like crystals.

The National Center for Hydro-Meteorological Forecasting anticipates strong cold air waves from December 2024 to February 2025, leading to prolonged severe cold and potential frost in northern mountainous regions.

While national temperatures from December to May 2025 are expected to align with multi-year averages, December temperatures in the northwest, central, and south-central regions may be 0.5-1 degree higher than usual.

Last year, Fansipan’s frost was first recorded on Nov. 26.

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