OVIEDO, Spain

Millions of people in Spain were warned to stay at home Sunday, as a slow-moving and powerful storm makes its way across the country.

While parts of Valencia, Andalusia and Catalonia have already seen flooding, people were trapped in their cars and other damage were seen, the most dangerous weather is expected to hit Madrid and Toledo in the evening. Both areas are under red alert for potential record-breaking rains.

“The message to people of Madrid is the best way to stay safe is not to go out on the streets … We are about to go through an anomalous and exceptional situation,” Madrid’s Mayor Jose Luis Martinez Almeida said on Sunday.

Many rail lines to and from Madrid, particularly medium distance and towards the Mediterranean coast have been cut off. The city has also closed as many traffic tunnels as possible, while Spain’s airport manager Enaire said the storm is having a “major impact” on flights.

In the Mediterranean, many ferry lines have been closed, as has the port of Valencia. Meanwhile, Madrid has shut down its parks and canceled professional football matches.

This comes as Sunday marks the final day of the summer holiday season for many Spaniards. The heavy traffic of people returning to their homes combined with intense rainfall has already caused several accidents on major highways.

Forecasts suggest that Madrid could see in a single day half the rain it usually gets in a whole year. Parts of Madrid and central Spain could see up to 200 liters (31 gallons) per square meter (10 square feet) over 24 hours. For Madrid, that would shatter the previous record set in 1972.

The rain has already started in Madrid and is expected to get heaviest this evening but last well into Monday.

While the areas of Madrid and Toledo are under red alert, much of southern and eastern Spain are also under orange or yellow warnings for strong winds, heavy rains and hail.

The city of Seville, which has not seen a drop of rain since early June, was hit with 57 liters per square meter on Sunday. There, emergency services dealt with around 200 related incidents.