Summer 2025 Climate Review

The Met Office's provisional figures for Summer 2025 show it will ‘almost certainly’ be the UK’s hottest on record, with average temperatures more than 1.5 °C above the seasonal norm. Across Europe, heatwaves pushed thermometers above 45 °C, leading to thousands of excess deaths and placing energy and water systems under severe strain. These events are not isolated but signals of a climate that is shifting faster than many had anticipated.

As the season comes to a close, this review looks at what the data reveals, how communities and infrastructure have coped, and what this summer tells us about the path ahead for climate resilience and the clean energy transition.

A New Normal for the UK

The UK has warmed by roughly 0.25 °C per decade since the 1980s. Summer 2025 featured four official heatwaves, widespread hosepipe bans, and drought declarations in multiple regions. Transport and housing struggled: speed restrictions and rail buckling risks returned on key routes, while homes lacking active cooling left many exposed. Reservoir stocks fell well below seasonal norms in several regions.

The Wider European Picture

Across Europe, the story has been just as severe. France closed nearly 1,900 schools at the peak of the heatwave, while Italy restricted outdoor work and issued red alerts for major cities including Rome and Milan. In Spain, June was the hottest on record, with Mediterranean Sea temperatures hitting 30 °C, six degrees above normal, creating a “heat dome” that locked hot air over the continent. Turkey, meanwhile, battled wildfires that forced the evacuation of around 50,000 people. Power outages linked to surging air conditioning demand hit parts of Italy, while rail services between Paris and Milan were disrupted by mudslides triggered by the heat. With Europe warming at roughly twice the global average, scientists warn that such extremes, once expected only later in the season, are arriving earlier, lasting longer, and placing unprecedented strain on health systems, infrastructure, and food security.

A Global Picture

The extremes of Summer 2025 were not confined to Europe. Canada endured one of its worst wildfire seasons on record, and Southern California suffered a highly destructive early-year fire series that killed dozens and displaced hundreds of thousands. Flash floods swept the U.S. Midwest and South, producing deadly inundations and warnings of generational-scale rain events. In Asia, India and Pakistan were struck by an early heatwave, with temperatures approaching 48 °C, placing immense stress on populations. Southern China experienced catastrophic monsoon rains, triggering deadly landslides, flooding, and disease outbreaks.

Key Incidents Testing Resilience: Wildfires

By late August, over 1.0 million hectares had burned across the EU which is the most since EFFIS records began in 2006, with major events in Greece, Portugal, Cyprus, and Turkey. Attribution scientists also find that climate change intensified the wildfire-favourable weather in parts of the eastern Mediterranean this summer.

What this summer says about resilience & transition

• Heat-ready homes & health. Retrofit shading/ventilation, passive cooling, and targeted cool-space access (schools, care facilities). Heat action plans saved lives where deployed; scale them.

• Water security. Drought planning needs regional nuance: groundwater and reservoir conditions diverged markedly across England; abstraction controls and leakage reduction remain essential. 

• Fire management. Expand prevention (fuel management, early detection), cross-border surge capacity, and community protections as burned area totals rise. 

Lessons for Resilience and Transition

Taken together, these events underscore a hard truth: climate change is no longer a distant forecast but a lived reality. From heatwaves and wildfires to floods and blackouts, resilience is being tested across every sector—healthcare, energy, transport, and agriculture.

For policymakers, the lesson is clear. Resilience planning must accelerate whether through heat adaptation in homes, upgraded energy grids with more storage and interconnections, or stronger emergency response systems. For businesses and investors, the imperative is to align strategies with the clean energy transition while preparing for growing physical climate risks.

Summer 2025 has offered a stark preview of what is to come. The challenge now is to turn warnings into action, building systems capable of withstanding the shocks of a climate that no longer behaves as it once did.

References

• Met Office: This summer will ‘almost certainly’ be warmest on record for the UK (26 Aug 2025)

• Met Office: State of the UK Climate

• Environment Agency: Water situation – July 2025 summary

• Reuters: Thames Water imposes hosepipe ban amid historic drought (14 Jul 2025)

• Reuters: France shuts schools, Italy limits outdoor work, Spain’s hottest June, Med off Spain record high (1 Jul 2025)

• Copernicus: European State of the Climate 2024

• Mercator Ocean: Mid-year highlights 2025 – Mediterranean Sea

• ANSA: Heat-induced blackout hits Milan area after Florence and Bergamo (1 Jul 2025)

• Reuters: European heatwave caused ~2,300 deaths across 12 cities in 10 days (9 Jul 2025)

• LSHTM: First analysis estimates number of heatwave deaths linked to climate change (9 Jul 2025)

• Reuters: Heatwaves in Spain caused 1,180 deaths May–July (14 Jul 2025)

• Reuters: Record wildfires burn >1 million hectares in EU (26 Aug 2025)

• The Guardian: EU wildfires worst year on record as season continues (22 Aug 2025)

• World Weather Attribution: Wildfire conditions in Türkiye, Cyprus & Greece made ~10× more likely by climate change (Aug 2025)

• The Guardian: Canada suffers one of its worst wildfire seasons on record (11 Aug 2025)

• Los Angeles Times: California wildfires kill dozens, destroy thousands of homes in January inferno (25 Jan 2025)

• Reuters: Warning of ‘generational’ floods as storms hit US Midwest, South (3 Apr 2025)