Notice

When initially published, data for 38 of the cities in this database contained errors. In those cities, the two datasets involved were never adjusted to be comparable. As a result, the temperature increase for those 38 cities was wrong, and in most cases far to high.

The data has since been corrected. Read more here →

Europe is warming, rapidly

An analysis of over 100 million meteorological data points, from 117 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 last century. Subarctic regions, Andalusia and southern Romania are most affected.

In Granada, Cordoba and Malaga, all Andalusian cities, the average yearly temperature in the 21st century was at least 1.5°C higher than in the 20th century. In Bucharest, capital city of Romania, temperatures increased by 1.4°C. The increase relative to preindustrial levels, a period often considered to be 1850-1900, is likely higher. By contrast, cities on the Atlantic shore saw the least amount of warming.

Map showing temperature differences in selected European cities, between 20th century and 21st century averages.
The rate of temperature increase in selected European cities.

These findings are the result of an analysis of 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.

Two datasets have been used for the analysis. The datasets are not directly comparable, and we have used a reconciliation algorithm to be able to make historical comparisons.

The fastest warming among Europe's largest metropolitan cities. The list shows the difference between 20th and 21st century average temperatures. Embed this list

Get the numbers

You are free to reuse data, and other resources linked on this site, provided you credit the source, the European Data Journalism Network.

Aggreggated data from this investigation is available in a Google Sheets spreadsheet.

Maps of different countries in nine languages and different sizes are avaiable a shared Dropbox folder.

To embed a toplistwidget, use the following url: https://www.onedegreewarmer.eu/topten?size=biggest&country=all&language=en&count=10, where country can be a two letter ISO code (use XK for Kosovo); language can be one of en, es, fr, de, it, pl, pt, ro, or sv; size is all, big, bigger, or biggest; and count is the number of items to show. Sample code:

<iframe src="https://www.onedegreewarmer.eu/topten?size=biggest&country=all&language=en&count=10" id="toplist" scrolling="no" style="overflow:hidden;height:36em;width:100%;border:none;margin-left:auto;margin-right:auto;" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/iframe-resizer/3.6.1/iframeResizer.js"></script>
<script>
    document.addEventListener("DOMContentLoaded", function(e){
      var iframe = document.getElementById('toplist');
      iFrameResize({checkOrigin: false});
    }, false);
</script>