Spain issues red heat alerts as Mediterranean sea temperatures near 30 °C and Valencia faces 44 °C

Red alerts across eastern and northwestern Spain

Spain's State Meteorological Agency (Aemet) issued red weather alerts on Tuesday and Wednesday as a surge of Saharan air pushed inland. On Tuesday, forecasters placed the Miño river basin in the northwestern province of Pontevedra under extreme danger, with peak temperatures projected to reach 40 °C. For Wednesday, Aemet extended red warnings to the coastal areas of Valencia and the northern zone of Alicante, where afternoon maximums could reach between 41 °C and 44 °C. High heat risks also covered southern Galician valleys, the central Ebro valley, western Catalonia, and the river basins of the Tajo, Guadiana, and Guadalquivir. Meteorologists identified a cut-off low pressure system (DANA) anchored southwest of the Iberian Peninsula, combined with an atmospheric ridge, as the primary atmospheric engine driving the hot air mass northwards.

Aemet spokesperson José Luis Camacho outlined the atmospheric dynamics behind the countrywide thermal spike.

The DANA located to the southwest of the Peninsula, associated with a ridge, fosters the entry and maintenance of warm Saharan air and conditions for very high maximum temperatures across much of the territory.

Mediterranean waters near 30 degrees Celsius

The persistent heat episodes across eastern Spain have raised concerns over sea surface temperatures in the western Mediterranean basin. Seawater in the Gulf of Valencia has hovered near 30 °C continuously, rather than registering brief isolated peaks. Jorge Olcina, a climatology professor and director of the Climatology Laboratory at the University of Alicante, warned that recurrent heat spells are driving sustained marine heating. Olcina explained that water temperatures in the gulf are approaching the 30 °C threshold on an unbroken basis.

These episodes continue to overheat the sea water, which is now on the verge of reaching 30 º C de forma continuada en el Golfo de Valencia.

According to Olcina, Wednesday's peak represents the final severe heat surge for the Valencian Community over the coming ten days. Atmospheric models project a thermal decompression starting on Thursday, which will lower regional temperatures back toward seasonal averages for mid-August.

Record warmth across the Valencian Community

The current spell follows an exceptionally hot opening to the month in eastern Spain. Aemet reported that the first fortnight of August 2026 was the warmest recorded in the Valencian Community since 1950, registering a temperature anomaly of +2.8 °C above normal baseline levels. Over the 24 hours leading into Tuesday, regional capital monitoring stations recorded elevated minimums and maximums across the territory. Castellón registered a minimum of 24.8 °C and a maximum of 34.1 °C, Valencia observed values between 22.7 °C and 34.5 °C, and Alicante recorded a low of 23.0 °C alongside a peak of 34.3 °C.

Coastal conditions and maritime forecasts

Weather conditions along the eastern seaboard feature light and variable breezes that shift during afternoon hours. In Castellón coastal waters, southerly winds of force 3 to 4 are forecast to turn easterly at force 3, generating slight to moderate seas in northern stretches before dawn. Valencia's waters expect easterly and southeasterly winds of force 3 to 4, easing to westerly winds overnight before picking up to force 3 to 5 by Wednesday afternoon. Along the Alicante coastline, northerly and northeasterly breezes of force 3 to 4 will shift to southerlies reaching force 5 later in the day, maintaining slight to moderate sea states. Isolated showers and storms may also develop over interior northern highlands during Tuesday afternoon.