Rainfall of 50-70 mm per hour could cause flooding at 11 locations, while rainfall of 70-100 mm per hour could affect 71 sites across the city.
In the event of rainfall exceeding 100 mm per hour for several hours, flooding is forecast at 220 locations across 54 wards and communes.
The city has instructed agencies to prepare response plans, warn residents, advise against unnecessary travel and implement measures to minimise disruption during severe weather.
Hanoi is also accelerating emergency drainage works and projects to improve the capacity of its urban drainage network.
Earlier this month, city officials said Hanoi’s drainage infrastructure currently meets only about 20 per cent of planned capacity.
Of the 48 major pumping stations required under the city’s master plan, only nine are currently operational, while flood-retention lake capacity has reached just 19 per cent of target levels, according to officials.