Temperatures are forecast to fall below 12 degrees Celsius in some mountainous areas.
The strong cold front arrived on 9 November, bringing temperatures down to below 20 degrees across much of the region.
The coldest conditions are expected overnight and early Tuesday, with lows of 15 to 18 degrees Celsius.
Meanwhile, showers are forecast to ease later today, giving way to colder, drier weather.
The cold air is also spreading southwards, affecting areas from Thanh Hoa to Quang Tri Provinces, while Hue City is expected to turn chilly tonight.
