From 1961 onwards climate extremes, including heatwaves, droughts, extreme rainfall, cold spells and fire‑prone weather, in Europe have increased in both frequency and intensity. “Europe has become prone to more frequent and intense multiple hazards; in particular to combinations of heatwaves, droughts, and extreme precipitation,” says CMCC researcher Jonathan Spinoni.

How often do extreme events occur alone, in sequence, and simultaneously? A recent study involving CMCC researcher Jonathan Spinoni, reveals that in recent decades more than three quarters of Europe has seen an increase in the frequency and intensity of at least two hazards for most of the year.

The study, titled Increasing frequency and intensity of single, multiple and concurrent meteorological hazards in Europe from a high-resolution dataset (1961–2020) and published in Environmental Research: Climate, uses a new pan‑European dataset at around 1.5‑kilometre resolution to track five types of extremes: heatwaves, coldwaves, meteorological droughts, extreme precipitation and fire‑favourable conditions.

By working at monthly timescales and such fine spatial detail, the authors identify where different hazards occur together and how these patterns have changed between the past period 1961–1990 and the more recent period 1991–2020.

“This study makes use of very high‑resolution climate data to investigate the occurrence of five climate extremes over Europe from 1961 onwards,” explains Spinoni. “Other than analyzing the changes in frequency of such five extremes, this study focuses on possible combinations of two or more hazards occurring in the same month.”

Heatwaves on the rise

Looking at single hazards, heatwaves show the most widespread increase across Europe in recent decades, with summer emerging as the key season. Most of Europe now experiences an occurrence of heat‑related hazards more than three times higher in 1991–2020 than in 1961–1990, especially during summer months.

Other extremes show more regional patterns. Extreme rainfall events have increased particularly over northern Europe and the United Kingdom, while droughts have intensified over central and southern Europe, and fire‑prone weather has increased over southwestern Europe, where the fire season has lengthened from spring to autumn.

In contrast, cold extremes have generally become less frequent, although in some months and regions coldwaves still show increases, with implications for agriculture and other sectors.

Europe more exposed to multiple hazards

Beyond single events, the study finds that Europe has become more prone to multiple hazards affecting the same areas repeatedly over the year. “More than three quarters of Europe has been subject to increased frequency and intensity of at least two hazards for most of the year, with the combinations between heatwaves, droughts, and extreme rainfall events standing out,” notes Spinoni.

Depending on the season and region, other combinations also emerge. Around 10% of the land area has experienced increases in both frequency and intensity of four different hazards – heatwaves, coldwaves, droughts and extreme precipitation – especially in spring and autumn.

The analysis shows that combinations involving heat and drought, heat and heavy rain, or all three together (hot–dry–wet) have also become more common over large parts of the continent.

Concurrent extremes and population exposure

A key novelty of the work is the focus on concurrent hazards – events that happen in the same month and year in the same location – because their combined impacts can be much larger than the sum of individual events. The researchers also estimate how many people are exposed to these concurrent extremes and how that has changed over time.

“As expected, concurrent heatwaves and drought events lead to the largest fraction of population exposed,” says Spinoni. Across Europe, the population cumulatively exposed to concurrent hot and dry conditions in 1991–2020 is about 2.7 times larger than in 1961–1990 in November (360 million versus 130 million people) and 4.7 times larger in August (1.3 billion versus 363 million people).

The number of people exposed to concurrent heatwaves and extreme precipitation has also increased sharply, especially in May, when the cumulated exposed population in 1991–2020 is 7.3 times larger than in 1961–1990 (440 million versus 65 million).

Fire‑prone hot and dry conditions show the strongest increases in exposure in summer, with the population exposed to concurrent hot–dry–fire weather in August rising from about 100 million to 450 million people, and to hot–dry–wet–fire conditions from 100 million to around 670 million people.

The study brings several innovations to the field of climate extremes and compound events. “The very high spatial resolution, combined with the length of the period analyzed, make this study innovative when dealing with concurrent hazards,” says Spinoni. The paper not only covers up to five types of extreme events but also details their seasonal behaviour, including combinations that are less often analysed, such as concurrent heat and heavy rain or cold and wet conditions in spring and autumn.

The work is the result of a close collaboration between CMCC and the European Commission’s Joint Research Centre, which developed the high‑resolution hydrological reanalysis dataset used in the study.

By showing how single, multiple and concurrent hazards have intensified across Europe over the past decades, the study underlines the need for preparedness and adaptation strategies that take compound extremes into account, rather than considering heat, drought, heavy rain or fire risk in isolation.

For more information:

Dosio, A., Koronaci, K., Spinoni, J., et al. (2026). Increasing frequency and intensity of single, multiple and concurrent meteorological hazards in Europe from a high-resolution dataset 1961–2020. Environmental Research: Climate, 5, 015003. https://doi.org/10.1088/2752-5295/ae1ce0