Spain faces 43ºC days as September starts like midsummer, and a hotter Med that can cook up storms

Spain is not getting the usual early-autumn breather. Meteorologist Samuel Biener at Meteored says a new heat dome will sit over the country from Wednesday to Saturday, sending thermometers back into midsummer territory just as autumn officially begins.

A strong ridge of high pressure will cook the air as it sinks, while a pocket of colder air west of the peninsula drags extra warmth up from North Africa. Friday’s maps even put the 28ºC line at about 1,500 metres over the centre of Spain, a high thermometer reading for September.

Where 40ºC is back on the cards

In land, in places like Badajoz, Caceres, Ciudad Real, Cordoba, Granada, Jaen, Lleida, Sevilla, Toledo and Zaragoza, all are in the 40 to 43ºC bracket later in the week. Other inland towns will not be far behind.

Saharan dust may haze skies over the south, south-east and Balearics, which can knock a degree or two off the afternoon peak. That is scant comfort after dark. Tropical nights are expected over wide areas, and some spots in Andalucia, on the Mediterranean coast, in the Balearics and in the Canary Islands may stay above 25ºC.

Scattered showers are only really possible today in the north and north-east. Clouds building over the Pyrenees and eastern Sierras between Tuesday and Wednesday may throw out isolated storms.

Why a “normal” trough can still turn nasty

Late-summer seas still hold a punch. Surface water hit a record 33ºC in places this season. Spain has already recorded record-warm coastal water this August, including 28.84ºC off Cabo de Gata in Almeria. That moisture is what Meteored’s Victor M. Gonzalez and Samuel Biener called “top-grade fuel” after a tornado tore through Pomas, just south of Carcassonne in France, on 24 August.

French specialists at Keraunos put winds on that six-kilometre track at 220-240 km/h. Roofs came off, stone walls were punched through and a thousand-year-old castle was left half-wrecked. Gonzalez’s warning for Spanish readers was blunt: the trough itself was “very typical”. What was not typical was the extra energy sitting over a scorching sea.

Warm water alone does not guarantee a wrecking ball of weather. High pressure parked until December would keep that stored heat bottled up. What you still need is a trigger, a trough or what is known in Spain as a ‘DANA’, to lift the air. That is why Gonzalez flagged “a couple of slightly delicate months” from now into autumn.

Supercells, waterspouts and Spanish precedent

Pomas, in France, spun out of a supercell, the rotating thunderstorm. Biener calls it “the queen of all storms”. Spain has already seen this before. A rare supercell tornado crossed Castellon province near El Toro in August 2024 after a heatwave break, with limited damage. Gonzalez says tornadoes of this type do form in Spain most summers and autumns, including on the coasts. Plenty stay as waterspouts. Paths are tiny and many miss houses. “Luck — or rather bad luck — that one hits a populated area”, he said.

September’s beginning, in short

A hot and summery start to September, with occasional patchy cloud cover and the chance of Saharan dust in the east, followed by probable stormy September weather made more extreme by hot seas all summer.

Keep an eye on AEMET warnings, treat waterspouts on the Med coast as the same family as land tornadoes, and follow running updates on Euro Weekly News weather. Official Spanish forecasts live at AEMET.