A rare and powerful atmospheric phenomenon has been blamed for the massive blackout that plunged large parts of Spain, Portugal and even parts of southern France into darkness on Monday (April 28). The unprecedented outage disrupted daily life for over 50 million people across the Iberian Peninsula, halting subways, grounding flights, severing phone lines and knocking out traffic lights and ATM machines.
According to Portugal’s electricity grid operator REN, the incident was triggered by “anomalous oscillations” in very high-voltage lines, caused by extreme temperature variations in Spain. This rare event, known as an “induced atmospheric variation,” led to synchronisation failures across the interconnected European electricity network, causing successive disturbances and widespread outages.
Spain’s PM says no conclusive information on cause of mass blackout
However, Spain’s Prime Minister Pedro Sanchez stated on Monday that there was still no definitive information regarding the cause of the widespread power blackout affecting much of the Iberian Peninsula.
The outage severely affected both Madrid and Lisbon, leaving government buildings, including Spain’s Parliament, subway systems, airports and major thoroughfares without power. In Barcelona, citizens took to the streets, directing traffic manually and scrambling to find working phone connections and battery-powered devices. Shops selling generators reported selling out within hours.
Airports operated on backup power, causing significant delays. TAP Air Portugal warned passengers not to head to airports until further notice. In Madrid, the Madrid Open tennis tournament was suspended mid-play, and train services across Spain and Portugal came to a halt.
Blackout could take 6-10 hours to fix
Spanish power distributor Red Eléctrica said restoring power across Spain and Portugal could take 6 to 10 hours, although full stabilisation of the grid could stretch over a week due to the complexity of the disturbance. By late afternoon, voltage was progressively being restored in the northern, southern, and western regions of the peninsula.
Eduardo Prieto, head of operations at Red Eléctrica, described the situation as “exceptional and extraordinary,” underlining the rarity and scale of the atmospheric phenomenon.
Authorities deny reports of cyberattack
Authorities from both Spain and Portugal confirmed there were no indications that the blackout was caused by a cyberattack. Portuguese Prime Minister Luís Montenegro and European Council President António Costa both emphasised that investigations were ongoing but ruled out any immediate cyber threats.
Emergency response by government
Spain’s Prime Minister Pedro Sánchez convened an extraordinary meeting of the National Security Council and personally visited Red Eléctrica to monitor the situation. Similarly, the Portuguese government held an emergency Cabinet meeting to coordinate their response.
Emergency services, hospitals and critical infrastructure across both countries switched to backup generators to maintain essential services, while police increased patrols to manage traffic and assist citizens stranded by the outage.
As power is gradually restored, experts warn that full normalisation of the grid could take several days. Authorities continue to assess the damage and implement measures to prevent future disruptions of such magnitude.