A cold front is quickly moving in from southern China to northern Vietnam, said the National Hydrometeorology Forecast Center.
From this evening northern provinces will experience a cold snap, with temperatures dropping to 16-20oC.
In some mountainous areas, it may drop 12-17oC, forecasters warn.
Within the next 2-3 days, it will be overcast in the Central Highlands and southern provinces, along with moderate and heavy rains in some areas, the center said.
The two regions are likely to receive northeast and easterly winds of force 2 or 3, the center said.