Overnight downpours caused localised flooding and a ravine to overflow in Aldaia, one of the towns hardest hit by the October 2024 disaster that killed more than 230 people. No injuries were reported.

"There is a bit of panic because of what happened. People are very scared," 64-year-old pensioner Jose Luis Ruiz told AFP in Aldaia.

"Everyone moved their cars away from the area. We set up barriers outside our doors. We had a bit of a sleepless night."

More than half a million students in Valencia had no lessons on Monday because 243 local councils in the region closed their schools as a precaution, regional education authorities said.

The regional capital, Valencia, also closed all public spaces, including libraries, parks, markets and cemeteries, local officials said.

National weather agency AEMET kept coastal areas of Valencia province under the highest red alert on Monday because of the risk of torrential rain.

It said as much as 180 millimetres of precipitation could fall in these areas in the space of 12 hours, possibly in just a few hours.

The weather agency downgraded its alert level to orange in other parts of Valencia as well as for the southern coast of the neighbouring region of Catalonia.

Last year's flood disaster sparked public anger over warning systems and emergency response, fuelling tensions between Spain's left-leaning central government and conservative regional authorities.

Residents continue to protest, accusing officials of failing to provide timely alerts.

Because a warmer atmosphere holds more water, climate change increases the risk and intensity of intense rainfall, and hence flooding.