Thousands of people have been evacuated from their homes in the Costa del Sol region of southern Spain as extreme rain and flooding drenches the area.
National weather office Aemet has placed both Malaga and the northeastern Catalonia region on the highest alert for strong rain expected to last until Friday.
The Malaga area, including the tourist resorts of Marbella, Velez and Estepona, is expected to take the brunt of the extreme weather phenomenon known as a "Dana".
Parts of the eastern Valencia area have also been placed on the highest alert, weeks after the area was devastated by flash floods that killed more than 220 people.
Several other regions in Spain remain braced for more heavy showers and low temperatures.
Up to 180mm of rain could fall in Catalonia in north-eastern Spain in just 12 hours, accompanied by thunderstorms along the coast near Tarragona, forecasters say.
Schools in the entire southern province of Málaga have been closed while many supermarkets have kept shutters down.
Footage circulating on social media showed the city's normally busy areas deserted as water flooded the streets.
Around 3,000 people living in close proximity to the Guadalhorce River have been told to leave their homes, the Regional Government of Andalusia has said.
Regional government's Minister of the Presidency Antonio Sanz said: "We have not evacuated entire towns, but rather specific areas linked to the riverbank.
"This decision has been communicated to the government of Spain in order to receive collaboration from the state security forces and bodies."
The severe weather alert in Málaga has also led to the opening tie of the Billie Jean King Cup between Spain and Poland being postponed, the International Tennis Federation said.
The two nations were set to play in Malaga on Wednesday.
Spain's meteorological agency Aemet has placed parts of the Andalusia region and the Balearic Islands on orange alert from now until Thursday.
Aemet warns of rainfall and storms that could be "very strong to torrential".
That orange alert is the second highest and it signals a significant meteorological event “with a degree of danger for normal activities”.
In Valencia, school classes and sports activities were suspended in some areas and sandbags piled up to protect the centre of the town of Aldaia.
However this second Dana weather system is not expected to be as dramatic as the red alert on 29 October, when the Valencia region in particular suffered an unprecedented loss of lives and material damage.
Elsewhere, rescue teams searching for the bodies of two young brothers who were swept away in the Valencia floods two weeks ago said their bodies had been found.
Izan Matías, 5, and Rubén Matías, 3, were pulled from their father Victor Matías's arms when the torrent ripped through their home in Valencia on the evening of 29 October.
Their aunt Barabara Sastre confirmed to the OceanNewsUK the boys had been found. Their bodies were recovered in different locations.
“My little angels, we have finally found you” one family friend, David Garcia, wrote online. “Two stars shine brighter in the sky.”
Yesterday, search teams had focused on part of the River Pollo about 6km (3.7km) from the family home.
The boys' uncle Iván had told the OceanNewsUK he was hugely grateful for all the support they had received and hoped his nephews would be found.
Volunteers from the Canary Islands and other parts of Spain had joined recovery specialists from Mexico, who normally work in the aftermath of earthquakes.
On Monday, the family dog was found dead in a garage in the town of Paiporta, more than 12km (7.4 miles) from their house in La Curra, a neighbourhood of Mas del Jutge.
Dana weather systems are formed when an area of low pressure gets "cut off" from the main flow of the jet stream.
This means that instead of moving through a region relatively quickly, they get blocked over the same area leading to persistent rainfall for several days.
Colder air high in the atmosphere meets warmer air flowing in from the Mediterranean which intensifies the storm.
On the first day of the COP29 climate summit on Monday, the Secretary General of the World Meterological Organisation Celeste Saulo said the recent floods in Spain were a strong message to the world.
"The incredible amount of rain in Spain was a wake-up call (about) how much more water a warmer atmosphere can hold," she said.
