An analysis of over 100 million meteorological data points, from 118 years of weatherdata, shows that every major city in Europe is warmer in the 21st century than it was in the 20th, with the average city being 1°C warmer compared to the last century.

We analysed over 100,000,000 data points made available by the European Centre for Medium-Range Weather Forecasts (ECMWF), an international organization which computes so-called “re-analyses” of weather data, based on a variety of sources such as weather stations, weather balloons, buoys and satellite observations. Such data is well-suited to study weather patterns over periods spanning over a century, because it harmonizes inputs from thousands of data sources and makes comparisons in time and space possible. While absolute values might differ from data collected at weather stations directly, especially because cities suffer from the “heat island effect”, meaning that temperatures within the cities can be up to 10°C higher than in their surrounding countryside, the overall trends are the same.

Main findings

• In 203 of the 558 cities analysed, 2018 stands out as the warmest year since 1900, and for a majority of the cities, 2018 was among the warmest five years measured. The data for this investigation was last updated in April 2019.
• In the Nordic and Baltic regions, in much of Andalusia and in South-Eastern Romania, average temperatures in the 21st century were already much warmer, sometimes by more than 1.5 degrees, than in the 20th century
• Higher temperatures, especially heat waves, were responsible for several thousands deaths since 2000. Despite the enactment of national heat plans in several countries, higher temperatures still cause excess deaths, not only in southern cities.

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