Major power outage hits Spain, Portugal and southern France after ‘rare atmospheric phenomenon’

A major power outage occurred in Europe on Monday, April 28, affecting Spain, Portugal, and parts of southern France. The blackout began around midday, resulting in widespread disruptions in major urban centers, including Madrid, Lisbon, and Barcelona.

In Spain, the national grid operator Red Eléctrica reported a sudden drop of over 10 gigawatts in electricity demand, representing more than one-third of the country’s total demand. As a result, metro services in Madrid were halted, traffic lights malfunctioned, and airports experienced operational difficulties.

Portugal’s national grid operator REN confirmed that the entire Iberian Peninsula was impacted. Portuguese authorities suggested that the disruption likely originated outside the country, potentially linked to issues within the Spanish distribution network.

In southern France, regions bordering Spain experienced brief but significant power losses. French grid operator RTE reported disturbances attributed to the interconnected nature of the European power grid, where failures in one region can have cascading effects across neighboring systems.

Portugal, Spain and France were hit by power blackouts causing Traffic jams, trains being haltedpic.twitter.com/K4BVYJcMS6

— Tornado guy (@fanofaliens) April 28, 2025

AVISO #Apagon #blackout
Reportan corte de energía generalizado en España Portugal y Francia
El metro de Madrid sin luz y el Aeropuerto Internacional de Barajas lo reportan inoperativo
Video vía @fanofaliens pic.twitter.com/6Dm0q4XXN3

— Geól. Sergio Almazán (@chematierra) April 28, 2025

The precise cause of the blackout remains under investigation. Preliminary reports suggest a failure in the interconnected European power grid, possibly exacerbated by high electricity demand and challenges in balancing renewable energy sources.

Emergency protocols have been activated to restore electricity and maintain essential services. Restoration efforts were ongoing as of the latest updates.

Updates

Further clarification from REN and ongoing investigations

19:00 UTC, April 28

In a follow-up statement issued late on April 28, REN suggested that a “rare atmospheric phenomenon” was responsible for triggering the Iberian Peninsula blackout and provided additional technical clarification regarding its potential effects on the grid.

According to REN, rapid and localized temperature fluctuations in Spain’s interior regions generated mechanical instabilities in several critical 400 kV lines, causing a rare form of conductor vibration. These vibrations, identified as a variant of aeolian vibration exacerbated by thermal gradients, led to transient shifts in electrical impedance along multiple transmission corridors.

As the disturbances propagated, they triggered an automatic desynchronization from the broader European electricity grid, managed by the European Network of Transmission System Operators for Electricity (ENTSO-E), in an effort to prevent a wider grid collapse.

ENTSO-E is an association of 39 electricity transmission system operators (TSOs) from 35 European countries. Established in 200

REN noted that the phenomenon, while rare, had been modeled theoretically in past risk assessments but had not been previously observed at this scale in real-world grid operations. The event was classified internally as a “Type 2 Induced Oscillation Event,” a designation within REN’s contingency protocols for rare but high-impact grid disturbances.

At a joint press conference with Portugal’s energy regulator ERSE, REN officials emphasized that there was “no indication of malicious interference, technical failure, or cyberattack,” reinforcing that the cause was atmospheric and mechanical in nature.

Nevertheless, they acknowledged that a full forensic analysis involving cross-border coordination with Spain’s Red Eléctrica and France’s RTE was still underway.

Meanwhile, Spain’s Red Eléctrica maintained a cautious position. In a separate update, CEO Eduardo Prieto said that their internal preliminary findings identified a “major external perturbation” affecting synchronization with ENTSO-E but did not confirm a specific cause. Prieto stated that comprehensive forensic studies of the grid’s behavior on April 28 were being conducted in collaboration with ENTSO-E’s Regional Security Coordinator (RSC) for Southwest Europe.

A spokesperson for ENTSO-E confirmed that the organization had initiated an urgent Event Investigation Procedure (EIP), a standard protocol for significant grid disturbances. The spokesperson added that final conclusions would require detailed cross-border data analysis, including SCADA logs, phasor measurement unit (PMU) data, and high-resolution frequency tracking records.

Independent grid experts contacted by Spanish daily El País and Portugal’s Público urged caution regarding the terminology used by REN. Dr. Ana Torres, a specialist in high-voltage transmission systems at the Polytechnic University of Madrid, explained that while environmental conditions can indeed induce mechanical conductor oscillations, the terminology “induced atmospheric vibration” lacks a defined standard in the engineering community.

“It is plausible that localized thermal gradients, combined with light wind conditions, caused conductor galloping or similar instability. However, this terminology seems adapted for public communication rather than technical documentation,” Dr. Torres said.

She also pointed out that other contributing factors, such as reduced grid inertia due to high solar penetration at midday, could have amplified the vulnerability of the network to such disturbances.

Initial estimates from REN indicated that while full grid stabilization was progressing ahead of schedule, final confirmation of complete recovery across all regions would not occur before May 1.

Restoration nears completion, cause under scrutiny

07:18 UTC, April 29

As of early Tuesday morning, April 29, the massive power outage that struck Spain, Portugal, and parts of southwestern France at 12:33 CET (10:33 UTC) on April 28 is largely resolved, with over 99% of Spain’s power and 80% of Portugal’s restored.

Approximately 33 to 34 million people were affected across the Iberian Peninsula and southwestern Europe.

The blackout, described as “exceptional and extraordinary” by Spain’s Red Eléctrica, lasted several hours in most areas. Full normalization is expected within days in Portugal due to the complexity of grid rebalancing. Andorra and parts of Belgium also reported brief outages.

The outage crippled critical infrastructure, halting trains, metro systems, and airport operations, including Madrid-Barajas Airport and Lisbon’s Humberto Delgado Airport. Traffic lights, ATMs, phone networks, and internet services were disrupted. Hospitals operated on backup generators, and the Madrid Open tennis tournament was suspended. Internet traffic in Portugal dropped by up to 90%, with average download speeds falling from 40 Mbps to 15 Mbps.

Spain declared a state of emergency on Monday evening, deploying 30 000 police officers to maintain public order.

While Portugal’s grid operator, REN, attributed the blackout to a “rare atmospheric phenomenon” this theory is now under heavy scrutiny.

An alternative theory under investigation involves a potential technical fault in the Spain–France interconnector. Kristian Ruby, Secretary General of EURELECTRIC, suggested that a fire damaging a high-voltage line between Perpignan and Narbonne might have contributed to the disturbance. However, France’s grid operator, RTE, stated that no fires were detected in the region during the period in question, casting doubt on this explanation.

Another possibility being examined concerns the stability of Spain’s renewable energy mix at the time of the outage.

With solar energy contributing approximately 60% of Spain’s electricity during midday on April 28, some experts suggest that the reduced grid inertia inherent to renewable-dominated systems could have made the grid more vulnerable to oscillations and synchronization issues. According to reporting by the Daily Mail, the lack of rotational inertia from traditional power plants may have exacerbated the network’s instability under environmental stress.

Speculation about a possible cyberattack was also raised in the immediate aftermath of the blackout.

While EU officials and the Portuguese government quickly dismissed the likelihood of sabotage, Spain’s National Cybersecurity Institute (INCIBE) has launched an investigation into potential vulnerabilities within the grid’s control systems. As of April 29, no evidence of cyber interference has been found, but the investigation remains active.

While this event is among the most severe power outages in Europe, it is not the largest recorded. The 2003 Italy blackout affected over 56 million people, encompassing the entire Italian Peninsula and parts of Switzerland. Additionally, the 2006 European blackout impacted more than 15 million customers across several countries, including Germany, France, and Spain.