As southern Spain sweltered in a burst of midday heat on Monday, the lights across the nation abruptly went out. Trains stopped mid-journey. Airport terminals descended into darkness. Mobile phone signals faded. And by nightfall, much of the Iberian Peninsula had declared a state of emergency.
The blackout, one of the largest in the region's history, plunged vast swathes of Spain and Portugal into chaos. But while engineers continue their painstaking investigation, a central question looms: did the weather cause the grid to buckle?
Spanish Prime Minister Pedro Sánchez has so far refused to draw conclusions, stating only that a “strong oscillation” destabilised the national grid and triggered a widespread collapse. But the timing - a spike in temperatures across southern Spain just before the outage - has drawn renewed attention to the stress that extreme weather can place on already vulnerable infrastructure.
Meteorological data shows temperatures soared rapidly around midday Monday, with parts of Andalucia recording spikes of 8°C within a single hour. Experts say such abrupt changes can sharply reduce the efficiency of overhead transmission lines, which sag when hot and can lose capacity - a risk factor for grid failures.
That instability may have played a role in Monday’s chain of events, which began shortly after 10:30am GMT and, within minutes, had severed Spain’s grid from the rest of Europe. The nation lost 15 gigawatts of electricity generation in just five seconds, Sánchez later confirmed - an astonishing figure representing 60% of national demand at that time.
Spain has been a poster child for renewable energy, sourcing 43% of its electricity from solar and wind. But Monday’s outage has revived old concerns that the country’s infrastructure has not evolved in step with its ambitions.
Portugal’s grid operator REN issued a statement linking the blackout to “a rare atmospheric phenomenon” caused by extreme temperature variation within Spain. While short on detail, the language was enough to further stoke debate around whether climate-linked instability is already manifesting more frequently in European grids.
In Madrid, where metro systems shut down and traffic signals failed, emergency services were forced to evacuate commuters from underground stations and redirect traffic in the absence of functioning lights. Across the country, shops closed early and hospitals ran on backup generators. At Lisbon and Madrid airports, hundreds of flights were delayed or cancelled as terminals operated on emergency power.
By nightfall, only about half the grid had been restored. Sánchez, addressing the nation at 11pm local time, urged calm and cautioned against speculation — but acknowledged the crisis had caused "anxiety in millions of homes" and dealt a serious blow to the economy.
Spain’s national grid operator, Red Eléctrica, said the cause of the “very strong oscillation” was still under investigation. While sabotage, cyberattacks and technical faults remain on the table, experts suggest climate-linked variables - from extreme heat to volatile renewable generation - can no longer be treated as secondary considerations.
In recent years, heatwaves have strained power grids from California to southern France. Monday’s blackout, while unprecedented in scale for Spain, is not without precedent in the broader context of climate-driven infrastructure stress.
The government has pledged support for affected regions and convened an emergency task force to analyse the event. Meanwhile, residents are bracing for continued disruption - and energy policymakers may find themselves confronting a new reality where climate resilience is no longer optional, but essential.
