Ruai, Mathare and Kibera are among 436 hotspots identified by Nairobi county as areas prone to flooding ahead of the upcoming El Nino rains.
Others include Njiru, settlements in Mukuru, Waruku in Kileleshwa and along the Nairobi River.
Nairobi's Disaster Management and Coordination chief officer, Bramwel Simiyu said the county government will also take the initiative to sensitise the population residing in the mentioned areas about the appropriate measures said to be taken during flooding.
Speaking on Wednesday, the director also noted that close to 200,000 people are at risk of being displaced due to the heavy rains.
"As part of our mitigation plan is that we're deploying our environment workers to continuously unclog the blocked drainages," Simiyu said.
"We have also tasked our subcounty teams to map out their priorities and resource requirements and come up with a budget. "
The chief officer also revealed that City Hall has plans for evacuating these areas and establishing temporary shelters as alternative measures.
Already, City Hall has recruited 3,500 youths to form the Green Nairobi team.
Their mandate is to unclog and clean drainages, as well as collect garbage to maintain the cleanliness of the city.
After seven years, Kenya is staring at another El Niño event.
This is after the World Meteorological Organisation on July 5, declared the onset of El Niño.
El Nino occurs on average every two to seven years, and episodes typically last nine to 12 months.
The phenomenon usually brings heavy rains to Kenya, as opposed to La Nina, which brings dry weather.
El Nino conditions are expected to persist up to the October-December 2023, rainfall season and may extend to the November to January season.
The 1997 El Nino rainfall had a devastating impact on agriculture, water resources, transport and communications and health sectors due to its uniqueness, intensity and destructive power.
During that period, several health facilities were physically destroyed while an upsurge of disease epidemics and an increase in morbidity and mortality rates were witnessed.
Last week, the Water Resources Authority asked Kenyans to be on the lookout for areas likely to be affected by the expected El Nino rains.