Yes

you do need a jacket based on the weather in St. Louis, MO, USA 1 second ago

Why? Because it's cold. simple as that.
46°F8°C & Partly Cloudy

Wind is 4 mph7 km/h from the SW, gusting to 11 mph17 km/h
March 29
5am46°F8°C5 mph8 km/h SWMostly Cloudy
6am45°F7°C4 mph7 km/h SPartly Cloudy
7am44°F7°C4 mph7 km/h SPartly Cloudy
8am44°F7°C4 mph7 km/h SPartly Cloudy
9am48°F9°C5 mph8 km/h SMostly Clear
10am54°F12°C7 mph11 km/h SMostly Clear
11am59°F15°C9 mph14 km/h SMostly Clear
12pm64°F18°C11 mph17 km/h SPartly Cloudy
1pm68°F20°C13 mph21 km/h SPartly Cloudy
2pm70°F21°C14 mph23 km/h SMostly Cloudy
3pm72°F22°C15 mph24 km/h SMostly Cloudy
4pm74°F23°C16 mph25 km/h SWindy
DateLowHighWindDayNight
March 2944°F7°C74°F24°C12 mph20 km/h from SPartly CloudyMostly Cloudy
March 3057°F14°C74°F23°C10 mph15 km/h from WMostly CloudyMostly Cloudy
March 3155°F13°C80°F26°C10 mph16 km/h from SMostly CloudyCloudy
April 162°F17°C76°F24°C9 mph15 km/h from SRainRain
April 245°F7°C63°F17°C13 mph21 km/h from NWDrizzleMostly Cloudy
April 340°F5°C52°F11°C16 mph25 km/h from NWDrizzleMostly Clear
April 437°F3°C61°F16°C7 mph11 km/h from NWClearClear

Yes

Low of 57°F14°C, High of 73°F23°C
Wind: 10 mph15 km/h
Precipitation: None

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