At least seven people died on Thursday in flash floods during torrential rains which pummelled Ivory Coast's Abidjan for two days.
This comes less than two weeks after 13 people were killed by a landslide nearby.
On Friday, the country's meteorological services warned more rain was expected through the weekend.
The administrative head of the Abidjan area, Vincent Toh Bi Irie, said on Facebook that "in some places, the rainfall could reach 300 millimetres (12 inches) today, or six times the threshold for a critical alert".
He urged residents not to go to regions where there is a risk of flooding and told people in areas prone to landslides to leave.
The West African nation is in the middle of its April to end of October rainy season which sometimes causes deadly floods and landslides.
On Thursday, Abidjan's weak drainage system was quickly overwhelmed.
Major thoroughfares were flooded and cars and debris were swept away. Residents in low-lying homes were forced to seek safety.
Amankou Gabin, the head of the civil protection unit, said the situation was made worse by poor construction over the years.
He said homes were built in storm basins where the rainwater was supposed to pass through to reach Abidjan's lagoon.
SOURCE: Reuters news agency