Drastic power fluctuations led to a widespread electrical failure that cast most of Spain and all of Portugal into darkness on Monday, marking one of the most serious blackouts in Europe in recent years.

While some areas in Spain started to gradually restore power by the afternoon, complete electric supply isn’t anticipated to return until at least the evening. This was confirmed by the grid operator, Red Electrica. The outage was linked to sudden changes in the network, referred to as “oscillations,” according to Eduardo Prieto, the company’s director of services, who chose not to go into the specifics of what caused them.

An emailed statement from the European Union Agency for Cybersecurity noted, “At this stage, preliminary investigations point to a technical or cable issue,” stressing that they are “closely observing” the situation and are in communication with national and EU authorities.

The power failure occurred shortly after 12:30 PM local time, impacting public transport, airports, and telecommunications. Data from Red Electrica indicated a sharp decline in power demand shortly after noon, dropping over 10 gigawatts, which exceeds a third of Spain’s usual daily electricity consumption. This unexpected outage took millions by surprise.

Nationwide blackouts are uncommon in Europe. In 2003, Italy experienced its largest power outage in decades when a failure in electricity lines from neighboring countries affected the entire nation, excluding Sardinia. Similarly, London faced a significant blackout in 2019 due to the simultaneous failure of a gas plant and an offshore wind facility.

Spanish Prime Minister Pedro Sanchez and Deputy Prime Minister Sara Aagesen convened an urgent meeting at the Red Electrica headquarters to seek answers.

“I urge everyone in Madrid to limit movement,” said José Luis Martínez-Almeida, the city’s mayor, via social media. “Traffic lights are out, and it’s essential that emergency services can navigate freely.”

It’s possible that a surplus of solar energy in the grid contributed to the incident. Recently, Spain has experienced an unprecedented number of hours with negative electricity prices as more solar and wind energy is integrated into the grid. However, this has not led to previous blackouts in the country.

The French grid operator RTE reported supplying 700 megawatts of power to Spain, with readiness to increase that to 950 MW as soon as the network could accommodate it. Residents in the French Basque Country experienced a brief loss of power before electricity was restored.

Despite the incident, stock markets in both nations continued to operate, with Spain’s Ibex35 retracting earlier gains shortly after the blackout began. The country’s competition agency CNMC delayed its decision on BBVA’s acquisition bid for Banco de Sabadell due to the blackout, as reported by news agency Efe, citing unnamed sources.

As of now, a cyberattack has not been completely ruled out, according to sources familiar with the investigation. Authorities are continuing to work on restoring the power network.

Public transport, traffic signals, and telephone services were largely non-operational in sections of Madrid, Barcelona, and Lisbon due to the outage, with train services largely suspended. The main airport in Madrid advised travelers to expect considerable delays.

An ATM out of order due to the power outage in Lisbon. Image: Zed Jameson/Bloomberg

Dylan Fraser, a resident of Virginia, USA, arrived at the airport in Lisbon to board a flight home, only to learn that his flight had been canceled and the airport was shut down.

“They informed us we had to leave,” he recalled while sitting at the bar of the Sofitel Hotel in downtown Lisbon. “I have no idea when I’ll be able to return.”

The Canary and Balearic Islands of Spain remained unaffected, but on the mainland, many companies sent workers home, resulting in city streets being filled with people as police managed traffic.

In Madrid, the metro system was evacuated, and office workers flooded the financial district. Ambulances raced down Castellana Avenue, while traffic agents used loudspeakers to guide vehicles and pedestrians. ATMs in the central area were out of service.

“This feels quite strange and unsettling,” remarked Ana López, who works in the Castellana financial district and left her office after being dismissed for the day.

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