Connected vehicle data is revealing local temperature differences across Germany, from the hottest cities in the southwest to rapidly rising temperatures in the Rhine-Ruhr region.
How hot is summer in Germany? A new analysis of anonymized vehicle data by CARIAD and NIRA Dynamics shows that the answer can vary significantly from one city to another.
Based on anonymized sensor data from more than two million connected Volkswagen Group vehicles, the analysis provides a detailed view of local temperatures across Germany and shows how vehicle data can complement traditional weather measurements with insights from the road network.
In summer 2026, Freiburg im Breisgau was the hottest major city, with an average daytime temperature of 27.30°C. Bremerhaven, at 21.33°C, was the coolest. That’s a difference of almost 6°C.
But the data reveals more than where it’s hottest. Compared with 2022, temperatures increased in 77 of the 80 cities analyzed, with the strongest increases concentrated around the Rhine and Ruhr. Cologne recorded the largest rise at +1.66°C.
Average summer daytime temperature 2026 compared to 2022
Increase from -0.28 °C (Berlin, blue) to +1.66 °C (Cologne, red)
Image: CARIAD
Seeing temperature in greater detail
Connected vehicles add another layer to our understanding of local conditions. Sensor data collected from vehicles already on the road can reveal small-scale temperature variations across the road network and in urban heat pockets, complementing traditional weather data.
For us at NIRA, the analysis is another example of the potential hidden in everyday vehicle sensor data. By turning vehicle sensor data into insights at scale, we can build a more detailed understanding of the roads and the environments around them.
Which German cities were hottest this summer? And where are temperatures rising fastest?
Explore the full analysis and Germany’s heat map in CARIAD’s original article →
(Germany's heat map: What are the hottest cities in the summer of 2026? | CARIAD )
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