According to the National Hydro-meteorological Forecasting Center, a new low-pressure trough in combination with a wind convergence will cause widespread rainfall in the region.
The north has been reeling from heavy rains for almost a week now under the impact of an inter-tropical convergence zone in combination with eastern winds.
On Monday the mountainous area should expect rainfall of 20-40 mm and up to 60 mm in some places, the center said.
Showers and thunderstorms will occur mostly at night from Wednesday to Saturday, and flooding should be expected in low-lying areas and landslides in the mountains.
U.S. weather forecast site AccuWeather expected Hanoi to experience temperatures of 25-32 degrees Celsius on average through the week, and the mountainous Sa Pa Town in the northwestern province of Lao Cai to see temperatures ranging between 15 and 22 degrees.