Yes

you do need a jacket based on the weather in Washington (Northwest Washington), District of Columbia, United States 1 second ago

Why? Because it's not very warm out.
52°F11°C & Cloudy

Wind is 7 mph11 km/h from the N, gusting to 18 mph29 km/h
April 25
5am51°F11°C7 mph11 km/h NEMostly Clear
6am50°F10°C8 mph12 km/h NEPartly Cloudy
7am49°F9°C8 mph13 km/h NEMostly Cloudy
8am49°F9°C9 mph14 km/h NEMostly Cloudy
9am50°F10°C9 mph15 km/h NEMostly Cloudy
10am52°F11°C9 mph15 km/h NEMostly Cloudy
11am54°F12°C8 mph13 km/h NEMostly Cloudy
12pm56°F14°C8 mph13 km/h NEMostly Cloudy
1pm58°F15°C7 mph12 km/h NEPartly Cloudy
2pm60°F15°C7 mph11 km/h NEPartly Cloudy
3pm61°F16°C6 mph10 km/h EMostly Cloudy
4pm61°F16°C6 mph10 km/h ECloudy
DateLowHighWindDayNight
April 2549°F9°C61°F16°C8 mph12 km/h from NEMostly CloudyPartly Cloudy
April 2644°F7°C66°F19°C8 mph13 km/h from EMostly ClearMostly Cloudy
April 2746°F8°C63°F17°C7 mph12 km/h from SECloudyMostly Cloudy
April 2852°F11°C84°F29°C6 mph9 km/h from SWMostly ClearMostly Clear
April 2962°F17°C90°F32°C4 mph6 km/h from SWMostly ClearMostly Clear
April 3065°F18°C88°F31°C7 mph11 km/h from SWPartly CloudyMostly Cloudy
May 164°F18°C85°F29°C5 mph8 km/h from NWMostly ClearMostly Clear

Yes

Low of 45°F7°C, High of 66°F19°C
Wind: 8 mph13 km/h
Precipitation: None

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