August 2026 was the warmest August on record and tied with July 2023 as the warmest month in the Copernicus Climate Change Service's ERA5 dataset, the service said on 10 September 2026. The global average surface air temperature was 16.96°C, 0.85°C above the 1991 to 2020 average and 1.65°C above the estimated 1850 to 1900 pre-industrial level. It was the first month above 1.5°C since November 2025.
The period from June to August 2026 was the joint warmest on record globally, on par with 2024. Copernicus attributed the heat to global warming combined with rapidly rising sea surface temperatures in the equatorial Pacific associated with strong El Niño conditions.
Record ocean temperatures
The average sea surface temperature over the extra-polar ocean, between 60°S and 60°N, was 21.07°C in August, the highest on record for the month and joint highest for any month, tied with March 2024. The highest daily value ever recorded for that domain, 21.11°C, also occurred during the month. Copernicus noted that some other datasets do not show the monthly value as a record.
Sea surface temperatures were exceptionally high across much of the tropical Pacific, where El Niño conditions are forecast to strengthen further, potentially into one of the strongest El Niño events on record. Copernicus said the effects were already visible over land, with conditions favouring the intensification of seasonal wildfires in Indonesia.
Western Europe's hottest summer
August marked the end of western Europe's warmest summer on record, surpassing the previous record from 2003. The region experienced a succession of early, persistent and intense heatwaves that began in May. For Europe as a whole, summer 2026 was the third warmest on record, behind 2024 and 2022. European land temperatures averaged 20.26°C in August, the fourth warmest August on record.
Much of western, central and eastern Europe was drier than average, with severe drought reported in France, the UK, Hungary, Romania and Serbia. Copernicus reported exceptionally low flows on the Rhine, Danube, Southern Bug and Dnieper in August. Over the summer, large stretches of the Seine, Rhône, Loire and Glomma recorded their lowest seasonal flows since the record began in 1992, with record-low conditions along the entire length of the Danube, Vistula and Rhine.
In contrast, western Iberia, the Alpine region and north-eastern Europe were wetter than average, with local flooding in some areas.
Energy system effects in Europe
The summer's heat and drought had direct effects on European power systems. An analysis of April to July data published in August found that hydropower output across a corridor from the Rhine to the lower Danube was about one fifth below normal, with Hungary down 53% in July, and that nuclear plants on the Danube cut output as river flows fell. In France, EDF shut reactors at Nogent-sur-Seine, Bugey and Golfech during a record June heatwave because of river temperature limits. Day-ahead power prices in central and south-eastern Europe rose through the summer.
Low Rhine levels also restrict barge transport of coal, oil products and other goods, raising logistics costs. Iberian hydro output, by contrast, ran well above normal after a wet first half of the year.
El Niño and 2027
El Niño is the warm phase of a natural cycle in the tropical Pacific. Strong El Niño events release heat from the ocean into the atmosphere and tend to raise global temperatures, with the largest effect typically felt in the year after the event peaks. The record years of 2016 and 2024 both followed strong El Niño events. Forecasters expect the current event to have its peak effect on global temperatures in 2027, raising the likelihood that 2027 will set a new annual record.
El Niño also shifts rainfall patterns. It is associated with drier conditions in Indonesia, Australia, southern Africa and parts of India, and wetter conditions in parts of South America and the southern United States. These shifts matter for hydropower in Brazil, southern Africa and South Asia, for coal and LNG demand in Asia, and for agricultural commodity markets.
Implications for energy markets
For power markets, a strong El Niño affects demand and supply. In India, weaker monsoon rainfall can raise power demand for irrigation pumping and cooling while lowering hydro output. In southern Africa, drought in previous El Niño years reduced output at the Kariba dam, which supplies Zambia and Zimbabwe, and led to long power cuts. In Brazil, rainfall patterns affect the large hydro fleet and the need for thermal generation.
For gas markets, a milder northern hemisphere winter, which El Niño can bring to parts of North America, would reduce heating demand. In Europe, the winter effect of El Niño is weaker and less predictable. Gas storage levels and the state of LNG supply after the disruption in the Strait of Hormuz remain more important drivers of European prices.
Cooling demand and grids
Higher global temperatures raise cooling demand across much of the world. The 2026 northern hemisphere summer brought record peaks in several power systems. India's peak demand reached 270.82 GW in May, PJM in the eastern United States set a preliminary all-time peak of about 168 GW on 2 July and ERCOT in Texas reached 91,134 MW on 22 July. Each system met demand, but emergency measures were needed in PJM. Hot nights, which keep cooling demand high after solar output falls, have become a growing concern for grid operators.
Wildfires
The dry conditions led to widespread wildfire activity in several European regions over the summer, Copernicus said. Wildfires threaten power lines and substations in rural areas and can force grid operators to de-energise lines, which in turn can reduce the transfer capacity available between regions at times of high demand.
Sea ice
Arctic sea ice extent ranked 12th lowest for August, with particularly low cover in the Russian Arctic sector, and Antarctic sea ice extent ranked fourth lowest, according to Copernicus.
What to watch
Copernicus said it would publish more analysis of Europe's summer at the end of September. Key indicators for the coming months include the strength of El Niño, autumn rainfall in central Europe and its effect on reservoirs and rivers, and seasonal forecasts for the northern hemisphere winter.