Portugal and Spain both issued warnings over the potential fresh floods, after inundations blocked hundreds of roads, disrupted trains and forced thousands to evacuate from the rising waters.
Spain and Portugal were hit with a third storm in just a matter of weeks on Saturday, as the Iberian peninsula struggles to recover from extended periods of heavy rain and deadly floods.
The latest depression, christened Storm Marta, has prompted the deployment of more than 26,500 rescuers in Portugal, where the weather has led three municipalities to postpone Sunday's presidential vote till next week.
Both countries have issued warnings over the potential fresh floods, after inundations blocked hundreds of roads, disrupted trains and forced thousands to evacuate from the rising waters.
Mario Silvestre, commander in Portugal's civil protection agency, warned that the forecast was "extremely worrying", warning gusts of wind could reach 110 kilometres per hour after Marta reaches the Portuguese coastline, along with landslides and flash floods.
Portugal was already reeling from the effects of Storm Kristin, which led to the deaths of five people, injured hundreds and left tens of thousands without power, when Leonardo hit earlier this week.
One person died during the passage of Storm Leonardo and 1,100 people were evacuated across the country, according to the authorities.
Parts of Alcácer do Sal were submerged after the Sado River overflowed, forcing residents to leave the city located 90 kilometres south of Lisbon.
Portugal's National Meteorological Institute (IPMA) placed the entire coastline on orange alert due to heavy sea conditions, with waves reaching up to 13 metres high.
Eight of the 18 districts on the mainland, located in the centre and south of the country, were also on orange alert.
"All river basins remain under severe pressure," particularly the Tagus River in the Lisbon region and the Sado River further south, a spokesperson for the National Civil Protection Authority told AFP.
A succession of atmospheric depressions saw Portugal's dams release "a volume of water equivalent to the country's annual consumption" in just three days, said Jose Pimenta Machado, president of the Portuguese Environment Agency (APA).
Portuguese Prime Minister Luis Montenegro warned the damage exceeded €4 billion.
Rainfall in Spain expected to be less 'exceptional'
In Spain, much of the country's south, particularly Andalusia, was placed on orange alert on Saturday, as was the north-west facing heavy rain and violent storms, said national meteorological agency Aemet.
But Aemet added it expected the rainfall to be less "exceptional" than seen in recent days during the Leonardo depression, which authorities say claimed two lives, including a woman swept away by a river in Andalusia and whose body was found on Friday.
Fresh rainfall Saturday in Andalusia comes on top of downpours which caused mass flooding, landslides and the evacuation of more than 10,000 people from their homes.
"The rivers have hit their limit," warned Juan Manuel Moreno, president of the Andalusia region, on X.
After flying over flood-hit areas in southern Spain near Cadiz on Friday, Prime Minister Pedro Sanchez warned that "difficult days" lay ahead for the region as a result of the "very dangerous" weather forecast.
Many roads remained closed as a precaution and rail traffic is largely suspended, according to the authorities, who have called on the population to limit their travel as much as possible.
Scientists say human-driven climate change is increasing the length, intensity and frequency of extreme weather events, such as the floods and heatwaves that have struck both countries in recent years.