Electricity has been restored to nearly all of Spain and Portugal following the massive blackout that began on Monday, April 28, 2025. By early Tuesday morning, power grid operators in both countries confirmed that supply was back to normal or near-normal levels.
Summary of the Incident
On April 28, 2025, Spain and Portugal experienced one of the largest and most disruptive power outages in recent European history. The blackout affected nearly the entire Iberian Peninsula, including major cities such as Madrid, Barcelona, and Lisbon, and even briefly impacted parts of southern France. The outage led to widespread disruptions in transportation, communications, healthcare, and daily life, prompting both countries to declare states of emergency2346.
What Happened?
The blackout began around 12:30 PM local time on Monday, April 28, 2025.
Within five seconds, Spain lost 15 gigawatts of electricity generation-about 60% of its national demand-causing a rapid and extensive collapse of the grid123.
The grid instability also fractured the interconnection between the Spanish and French electricity systems, compounding the impact1.
Possible Causes Under Investigation
Authorities in both countries have stated that the precise cause of the outage is still under investigation, and no definitive explanation has been confirmed yet1236. However, several potential contributing factors have been discussed:
Grid Instability and Synchronization Failure: Portugal’s grid operator, REN, attributed the blackout to a “fault in the Spanish electricity grid,” specifically citing “extreme temperature variations in the interior of Spain” that caused “anomalous oscillations in the very high voltage lines (400 kV),” a phenomenon known as “induced atmospheric vibration.” These oscillations led to synchronization failures between the interconnected European electrical systems, triggering cascading disturbances256.
Rare Atmospheric Phenomenon: REN described the event as being related to a rare atmospheric phenomenon, but Spain’s national meteorological agency reported no unusual weather or temperature fluctuations on the day of the blackout, casting doubt on this explanation2.
High Share of Renewables and Grid Management Complexity: Spain’s rapid increase in renewable energy generation (56% of electricity in 2024) has made grid management more complex, with greater fluctuations in supply and demand. Experts note that integrating large amounts of renewables can increase the risk of instability if not carefully managed, though there is no direct evidence that oversupply triggered this specific blackout2.
Nuclear Plants Not Operating: An energy expert pointed out that Spain’s nuclear plants were not operating at the time, which may have left the grid more vulnerable to sudden imbalances1.
What Has Been Ruled Out?
Cyberattack: While some speculated about the possibility of a cyberattack, there is currently no evidence to support this, and authorities have not confirmed such a scenario2.
Weather Extremes: Spain’s meteorological agency found no evidence of extreme weather or sudden temperature changes that could explain the outage2.
Current Status
Power was restored to most of Spain and Portugal by early Tuesday, April 29, 2025, though transportation and some services continued to face disruptions13.
Both governments and grid operators are conducting detailed investigations, and a full explanation is expected to take weeks or months as forensic analysis of grid data continues23.
The April 2025 power cuts in Spain and Portugal were caused by a sudden and massive loss of electricity generation in Spain, which destabilized the grid and led to cascading failures across the interconnected systems of the Iberian Peninsula and parts of France. The most likely technical explanation involves rare oscillations in high-voltage transmission lines-possibly linked to atmospheric conditions or grid management challenges-but the exact cause remains under investigation. Both countries’ leaders and grid operators have cautioned against speculation until a thorough analysis is complete1236.
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