UK power grid faces blackout risk from rising summer heat, experts warn

Extreme heat could trigger Spain-style blackouts across UK power grid

Infrastructure not built for climate extremes may fail under future summer conditions

The UK’s electrical grid may be heading for crisis, with rising summer temperatures threatening to overwhelm key components of the system and triggering widespread power outages, according to new expert analysis. A recent study by consultancy Ricardo, in partnership with the UK government, has highlighted severe vulnerabilities in the country’s energy infrastructure as the climate continues to warm.

Transformers, underground cables, circuit breakers, and service lines are among the grid components most exposed to heat-related failure. These assets, many of which were designed for significantly cooler conditions, are struggling to adapt to heat waves that are becoming increasingly common and intense.

National infrastructure not built for a 40°C future

The UK's Met Office projects that summer temperatures of 40°C (104°F) or higher could occur every three to four years by the end of the century without urgent global action to cut emissions. But much of Britain’s energy system was designed for moderate seasonal variation, not for frequent extremes.

According to the Ricardo report, once ambient temperatures exceed 40°C, transformers begin losing capacity and risk critical failure. In regions such as East Anglia and the South East, where future heat extremes are likely to be most severe, the risk of “high impact” energy infrastructure failures is significantly elevated.

“These components weren’t engineered with today’s heat extremes in mind,” says Ryan Hogarth of Ricardo. “Some may simply stop working, while others will only operate at reduced capacity, limiting electricity supply at the very moment demand spikes.”

Strain on the system is growing fast

The UK’s grid is already showing signs of stress. In July 2022, the country experienced its first-ever 40°C heatwave. At the time, grid operators were forced to reduce capacity to prevent overheating, despite soaring demand for cooling systems. Analysts at Cornwall Insight later revealed the system came “very close” to experiencing an electricity shortfall.

This growing vulnerability will likely worsen as more households and businesses install air conditioning—placing even greater pressure on an infrastructure never intended for such loads. “We’re heading for a future where electricity demand during summer may outstrip winter levels,” says Hannah Bloomfield at Newcastle University.

“At present, if there's some stress on the grid, we can usually manage it with curtailments or load balancing,” she explains. “But in future, with much higher cooling demand, a heat wave could cause serious grid strain and push it beyond its limits.”

Lessons from Europe’s worst blackout in 20 years

The risk is not theoretical. Just last month, Spain and Portugal experienced the worst blackout in Europe in two decades. While the exact cause is still under investigation, early indications suggest it was triggered by a simultaneous loss of multiple generators—leading to a cascading failure across the wider system.

The UK could face a similar scenario if multiple grid components fail at once under extreme heat, warns Keith Bell of the University of Strathclyde. “When the system is operating near its thermal limit, one failure can cascade into another before there's time to react,” he says. “It’s not just individual outages that matter—it’s the combination that can trigger systemic collapse.”

Calls for urgent adaptation and investment

Despite the mounting risks, energy experts say there has been limited investment in heat-resilient infrastructure. Modernizing transformers and reinforcing vulnerable regions of the grid will require significant funding, long-term planning, and coordination across government and private utilities.

“Climate change is no longer a future problem—it’s here,” says Bell. “And unless the grid is adapted to meet it, blackouts will become a recurring feature of British summers.”

Stay tuned to The Horizons Times for continuing coverage on climate resilience, infrastructure adaptation, and the future of energy in a warming world.