Severe flooding has hit Barcelona, with a red alert warning of "extreme danger" from torrential rain.
Mobile phones received a message forecasting "continued rainfall" on the southern outskirts of the city.
People are being warned to avoid canals - and gorges which would normally be dry.
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Oscar Puente, Spain's transport minister, said he was suspending all commuter trains in northeastern Catalonia, following a request from civil protection officials.
The region has a population of eight million people.
"Do not travel unless strictly necessary," they are being told.
Footage on social media shows heavy rainfall overwhelming stairwells and covering streets with water.
Dozens of flights have been cancelled at El Prat airport after the terminal building was flooded.
It comes after at least 217 people were killed in flash floods across eastern Spain, with search teams continuing to scour flooded areas for bodies.
People were trapped in cars, homes and businesses as the waters surged through the disaster zone last week.
Six days later, the search and rescue operation continues for an unknown number of missing people, with thousands of soldiers brought in to help.
And as communities continue to reel from the catastrophic floods - and mourn their losses - more rain is forecast for parts of the country.
Much attention has been paid to an underground car park in Aldaia, where emergency services have been trying to drain the floodwater to gain access.
There had been fears that dozens of bodies could be found inside the car park after people died while trapped by the rising waters at the Bonaire shopping centre.
However, firefighters have downplayed the situation, Spanish media reported.
"Since yesterday afternoon we were able to get in with canoes, boats, drones and on foot," one of the firefighters told El Pais.
"Yesterday we went through the entire car park and luckily we haven't found any bodies."
They said that could change as the car park empties, but that at the moment the cars are all empty.
Read more:
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There has been anger at the response from authorities and a group of survivors hurled mud and insults at Spain's King Felipe when the monarch visited one of the worst-affected towns.
By the time authorities sent alerts to mobile phones warning of the seriousness of the flooding, and asking people to stay at home, many were already on the road or in places like underground garages that became death traps.
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Valencia's MotoGP race, which had been scheduled for later this month, has been cancelled after floods wrought destruction on the track.
Thousands of volunteers have been helping to clear away thick layers of mud from streets and homes.