Europe's Hottest Summer: 2.5°C Above Average

Western Europe experienced its hottest summer on record, with an average temperature of 21.7°C, 2.5°C above the 1991-2020 baseline, surpassing the 2003 record. Extreme heat also broke records in May and September, and Swiss glaciers lost 5.5% of their ice in the first eight months of 2026.

The 2026 summer entered climatology as the hottest in Western Europe. The average temperature from June to August was **21.7°C**, **2.5°C** above the **1991-2020** reference period. The previous record from 2003 has been surpassed. This was not an isolated monthly anomaly: heat persisted well beyond the core summer, with daily temperature records also set in May and September. For all European regions combined, this was the third warmest summer on record.

Summer conditions arrived unusually early. The first major heatwave hit much of Western Europe by late May, with exceptionally hot situations persisting throughout the summer months. This persistence had a measurable physical impact: **52%** of the continent was exposed to at least "very strong" thermal stress conditions by the end of the season, equivalent to a heat index of **38°C** or more. Thermal stress indicates how meteorological factors affect the human body and expose people to serious health risks, including heatstroke.

## Persistent heat breaking records outside summer

The geographic extent and duration of the heat were equally notable. In 2026, **17 days** were recorded where at least **60%** of Western Europe experienced temperatures above **30°C**. The comparison with previous years is eloquent: in 2003 there were 11 days, and in 2025, only 7. That is, extreme heat was not only more intense, but more sustained over time and broader in territory.

The Copernicus report, the European Union's Earth observation programme, highlights that Europe experienced a summer with accumulated extreme climate phenomena. In large parts of the continent, unprecedented heatwaves, widespread droughts, exceptionally low river flows, and unusually warm sea temperatures were recorded simultaneously. Samantha Burgess, head of the climate strategy at the European Centre for Medium-Range Weather Forecasts, noted that these factors went beyond temperature records and affected water availability, energy systems, transport, ecosystems, and human health.

## Swiss glaciers lose 5.5% of ice in eight months

One of the most visible effects of extreme heat is in the Alps. Swiss glaciers shrank by **5.5%** in the first eight months of 2026. This loss brings the total glacial ice retreat since 2021 to **19.4%**. The transformation of the Alpine country is drastic: large white glaciers have turned into lunar-looking rocky extensions. The lack of winter snowfall and abnormally high summer temperatures caused a retreat almost comparable to the 2022 record, according to data from the **Glamos** glacier monitoring network and the Swiss Academy of Sciences.

Matthias Huss, glaciologist and director of the Glamos network, was blunt in evaluating the data: "Ice loss has doubled in the last five-year period. We did not expect to see such enormous loss, and even less so concentrated in time; it is much faster than forecasts indicated." Researchers concluded that the rate of melting leaves Alpine glaciers no chance of surviving in the long term. Although glaciers worldwide are shrinking, the rate of loss is higher in the Alps. Permafrost thaw is destabilizing mountain slopes, posing a danger to mountaineers and hikers.

This danger materialized during the tourist season. An unusual number of rockfalls in the Alps caused at least three deaths: two Czech climbers were hit by rocks in July, and a French mountain guide trainee died in August due to a sudden rockfall in the Mont Blanc area.

## Drought, fires, and rivers at minimums

Prolonged and severe drought conditions across Europe laid the groundwork for the summer with the lowest river flows the continent has recorded since records began in **1992**. In July and August, record or near-record minimum river flows were recorded simultaneously in many of Europe's major rivers, including the **Rhine**, **Danube**, **Po**, **Loire**, **Rhône**, and **Seine**. This caused serious disruptions in multiple sectors, including freight transport, affecting supply chains, while exerting increasing pressure on irrigation, nuclear reactor cooling, hydroelectric power generation, and freshwater availability.

The wildfire season was exceptionally active. By September 2, the burned area across the European Union was nearly double the average for the **2006-2025** period for that time of year, trinc especially extensive activity in Spain and France. Data from Copernicus's Atmospheric Monitoring Service (CAMS) showed that wildfire emissions in Europe in late summer were among the ten highest since 2003, exposing millions to dangerous levels of air pollution.

Europe's seas also maintained exceptionally warm temperatures throughout the 2026 summer. Record or near-record surface water temperatures were recorded along much of the Atlantic coast and in the western and central Mediterranean. High sea temperatures were accompanied by intense to exceptional marine heatwave conditions, defined by prolonged periods of unusually warm ocean temperatures. These marine heatwaves can intensify heat in adjacent coastal areas by limiting nighttime cooling and increasing humidity, exacerbating thermal stress.

## Spain: Hottest summer in 150 years

The Copernicus report aligns with analyses by Spain's State Meteorological Agency (Aemet). Rubén del Campo, Aemet spokesperson, summarized the situation: "The 2026 summer has been the hottest in Spain in at least 150 years, with no fewer than **61 days** under heatwave between June 20 and September 7. A unprecedented situation." Full summer conditions began in mid-May and persisted through much of September, allowing for a four-month or four-and-a-half-month summer.

Del Campo added that it was the third driest summer in the series, which created water stress and dryness conditions that elevated fire danger to extreme levels for much of the season in many areas. "Unfortunately, we have seen how these high dangers translated into large wildfires. Although other non-meteorological factors, such as forest management, influence this problem, it is undeniable that anthropogenic climate change is favoring situations that increase wildfire danger," he concluded.

The economic impact of this summer extends across multiple fronts: compromised river transport, pressured nuclear reactor cooling, diminished hydroelectric generation, and Alpine tourism seeing its main attraction disappear. Swiss glaciers, which feed rivers and freshwater reserves, are retreating at a rate scientists consider irreversible. The question is no longer whether there will be another summer like this, but when it will happen again.