Spain’s transport minister, Oscar Puente, suspended all commuter trains in northeast Catalonia.
“Do not travel unless strictly necessary,” the region’s population of eight million people were told.
Footage on social media shows heavy rainfall overwhelming stairwells and covering streets with water.
Around 50 flights due to take off from Barcelona’s partially-flooded El Prat airport were cancelled or severely delayed, while 17 due to land were diverted, airport operator AENA said.
Several major roads were closed due to flooding.
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 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.
Source: https://news.sky.com/story/extreme-danger-red-alert-for-barcelona-warns-of-more-rain-on-the-way-with-spain-still-reeling-from-deadly-floods-13248153