Spanish and Portuguese authorities are bracing for the impact of Storm Leo, suspending schools in some areas and warning against travel, Reuters reports.
Leo comes just a week after deadly Storm Christine devastated the Iberian Peninsula.
Spain's state weather agency AEMET has predicted that parts of the southern Sierra de la Grazalema could receive a year's worth of rain as a result of the storm.
Authorities are worried about increased risk of flooding as ground remains waterlogged from previous storm and heavy rains last month.
Spain recorded 119.3 mm of rainfall in January, 85% above the 1992-2020 average, according to the Environment Ministry, making it the second wettest January of the 21st century.
The regional government in the southern autonomous region of Andalusia urged residents to avoid unnecessary travel and said public safety warnings could quickly escalate to the highest level of alert as the storm developed.
Face-to-face classes were suspended across the region, except in the province of Almeria, and Spain's military emergency services are on standby for rapid response, including flood rescues, stabilising areas prone to landslides and monitoring tailings dams at risk of overflowing.
Day centres for the elderly and disabled were closed, and Local authorities in the affected areas were advised to cancel outdoor sports activities. Around 3,000 people were evacuated from the most flood-prone areas.
The high-risk regions are Grazalema, Campo de Gibraltar, Ronda and parts of Jaén, where residents received mobile phone warnings of potential heavy rainfall.
Emergency teams, along with two planes and two helicopters, have been dispatched to monitor flood-prone areas and provide real-time updates.
In Portugal, the national civil protection service raised its alert level to the highest level after its commander warned of a "very complex" weather situation.
The Portuguese Armed Forces deployed up to 3,000 personnel and 42 inflatable boats with marine teams to flood-prone sections of the country's main rivers as weather conditions were expected to worsen during the week.