Aside from the depths of winter, the climate in the Bonn, Germany is relatively mild. Average high temperatures in the winter are in the low to mid 40s, while average lows are in the low to mid 30s. Average summer highs are in the low to mid 70s. Average summer lows range in the mid 50s. Precipitation falls pretty evenly throughout the year, although there is a greater chance of precipitation during the winter months of December and January.

Your best bet when planning a trip to Bonn may be to travel in the late spring or early autumn. Not only is the weather likely to be more pleasant during this time period, but it will also help you avoid the tourist onslaught  during the summertime when Germany, and all of Europe for that matter, literally crawls with backpackers.

Bonn Weather - 5 Day Forecast