Yes

you do need a jacket based on the weather in Bonn, Germany 1 second ago

Why? Because the drizzle is not enough rain to call it "raining," but enough to make you a little soggy!
63°F17°C & Drizzle

Wind is 5 mph8 km/h from the Northwest, gusting to 13 mph21 km/h
July 27
4pm63°F17°C5 mph8 km/h NorthwestDrizzle
5pm61°F16°C6 mph9 km/h NorthwestDrizzle
6pm60°F16°C5 mph9 km/h NorthwestDrizzle
7pm60°F15°C5 mph9 km/h NorthwestCloudy
8pm59°F15°C6 mph10 km/h NorthwestCloudy
9pm58°F15°C6 mph10 km/h NorthwestCloudy
10pm58°F14°C6 mph10 km/h NorthwestCloudy
11pm57°F14°C6 mph10 km/h NorthwestCloudy
July 28
12am57°F14°C6 mph10 km/h NorthwestCloudy
1am57°F14°C7 mph10 km/h NorthwestCloudy
2am58°F14°C7 mph12 km/h NorthwestCloudy
3am60°F15°C8 mph13 km/h NorthwestCloudy
DateLowHighWindDayNight
July 2660°F16°C73°F23°C5 mph7 km/h from NorthwestRainDrizzle
July 2757°F14°C70°F21°C9 mph15 km/h from NorthwestDrizzleRain
July 2855°F13°C70°F21°C5 mph8 km/h from WestDrizzleMostly Cloudy
July 2957°F14°C72°F22°C7 mph11 km/h from NorthwestPartly CloudyPartly Cloudy
July 3053°F11°C73°F23°C4 mph7 km/h from WestMostly CloudyMostly Cloudy
July 3159°F15°C71°F22°C4 mph6 km/h from WestRainRain
August 158°F14°C69°F21°C5 mph8 km/h from NorthwestDrizzleDrizzle

Yes

Low of 56°F14°C, High of 70°F21°C
Wind: 9 mph15 km/h
Precipitation: 46% rain

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