As the westernmost city in Germany , with humid weather, mild winters, and warm summers. Because of its location north of the Eifel and the High Fens and its subsequent prevailing westerly weather patterns, rainfall in Aachen (on average 805 mm/year) is comparatively higher than, for example, in Bonn (with 669 mm/year). Another factor in the local weather forces of Aachen is the occurrence of Foehn winds on the southerly air currents, which results from the city’s geographic location on the northern edge of the Eifel.
Because the city is surrounded by hills, it suffers from inversion-related smog. Some areas of the city have become urban heat islands as a result of poor heat exchange, both because of the area’s natural geography and from human activity. The city’s numerous cold air corridors, which are slated to remain as free as possible from new construction, therefore play an important role in the urban climate of Aachen.
The January average is
3.0 °C (37 °F), while the July average is 18.5 °C (65 °F). Precipitation is almost evenly spread throughout the year.