The summer of 2026 has been hot, but it affects German cities differently. An analysis of anonymized vehicle data by CARIAD, the software company of the Volkswagen Group and its Swedish subsidiary NIRA Dynamics shows:
The highest average summer daytime temperatures were measured in southwestern Germany in 2026. Freiburg im Breisgau is at the top with 27.30 °C, followed by Mannheim with 27.10 °C and Karlsruhe with 26.97 °C. Ludwigshafen am Rhein, Heidelberg and Heilbronn are also well above the average of major German cities.
As expected, cities in northern Germany and on the coast are at the lower end of the temperature ranking. Bremerhaven has a temperature of 21.33 °C, Kiel 21.43 °C and Rostock 21.48 °C. The gap between the hottest and the coolest city is thus just under 6 °C.
Established weather providers already offer high-quality measurements and forecasts. Anonymized sensor data from connected vehicles complement them as they can capture small-scale temperature variations directly on individual roads, or in urban heat pockets. More than two million connected vehicles from the Volkswagen Group provide anonymized data on road conditions and temperatures.
"Sensor data from connected vehicles forms an important basis for us to develop future driving functions. But it also helps us to understand conditions on and around the road more precisely. In summer, for example, it shows where heat is particularly intense. This improves mobility and can help us better assess local risks related to road conditions." says Sebastian Franke, Product Owner Chassis & Road Conditions at CARIAD.
While the highest summer temperatures are measured in the southwest in 2026, the strongest increases over the past four years are found mainly in cities in the Rhine and in the Ruhr region. Cologne is at the top with an increase of 1.66 °C, followed by Leverkusen with +1.61 °C and Mülheim an der Ruhr with +1.56 °C.
Lower temperature increases were seen mainly in eastern Germany. Even there, however, the summer has become cooler since 2022 in only three cities, and only slightly: Berlin (-0.28 °C), Potsdam (-0.21 °C) and Magdeburg (-0.08 °C). Higher temperatures were measured in the 77 other German cities.
In 77 out of 80 major German cities, the summer of 2026 has become hotter
Average summer daytime temperature 2026 compared to 2022
Increase from -0.28 °C (Berlin, blue) to +1.66 °C (Cologne, red)
Heat is increasingly not just a southwestern issue. While the hottest cities in 2026 are primarily located in Baden-Württemberg, Rhineland-Palatinate, and Hesse, the strongest temperature increase compared with 2022 is notably concentrated in western Germany, especially along the rivers Rhine and Ruhr.
Cities near the coast remain cooler, as expected. Bremerhaven, Kiel, Rostock, Lübeck, and Hamburg are all among the ten coolest major cities in Germany.
The differences between the cities are considerable. On an average summer day in 2026, there is a temperature gap of almost 6 °C between Freiburg im Breisgau and Bremerhaven. Looking at the temperature increase compared with 2022, the range is almost 2 °C: from a summer that was 0.28 °C cooler in Berlin to one that was 1.66 °C hotter in Cologne.
The 10 hottest cities in Germany
1
Freiburg im Breisgau
27.30 °C
2
Mannheim
27.10 °C
3
Karlsruhe
26.97 °C
4
Ludwigshafen am Rhein
26.87 °C
5
Heidelberg
26.86 °C
6
Heilbronn
26.67 °C
7
Frankfurt am Main
26.37 °C
8
Offenbach am Main
26.35 °C
9
Darmstadt
26.35 °C
10
Würzburg
26.24 °C
Average summer daytime temperature in 2026
The 10 coolest cities in Germany
1
Bremerhaven
21.33 °C
2
Kiel
21.43 °C
3
Rostock
21.48 °C
4
Lübeck
21.87 °C
5
Oldenburg
22.04 °C
6
Hamburg
22.19 °C
7
Bremen
22.45 °C
8
Remscheid
22.71 °C
9
Chemnitz
22.85 °C
10
Salzgitter
22.90 °C
Average summer daytime temperature in 2026
The 10 cities with the highest temperature increase
1
Cologne
+1.66 °C
2
Leverkusen
+1.61 °C
3
Mülheim an der Ruhr
+1.56 °C
4
Krefeld
+1.55 °C
5
Duisburg
+1.53 °C
6
Bonn
+1.52 °C
7
Bochum
+1.50 °C
8
Koblenz
+1.50 °C
9
Essen
+1.50 °C
10
Düsseldorf
+1.49 °C
Average summer daytime temperature 2026 compared to 2022
The 10 cities with the lowest temperature increase
1
Berlin
-0.28 °C
2
Potsdam
-0.21 °C
3
Magdeburg
-0.08 °C
4
Dresden
+0.02 °C
5
Wolfsburg
+0.04 °C
6
Göttingen
+0.06 °C
7
Jena
+0.07 °C
8
Chemnitz
+0.10 °C
9
Salzgitter
+0.15 °C
10
Brunswick
+0.18 °C
Average summer daytime temperature 2026 compared to 2022
About the database
The evaluation covers German cities with at least 100,000 inhabitants. It is based on measured summer air temperatures in the area surrounding the vehicles, for June and July of each year, during daytime hours from 8 a.m. to 8 p.m.
