Yes

you do need a jacket based on the weather in Southampton SO16, UK 1 second ago

Why? Because it's cool. Pleasantly cool, but cool.
54°F12°C & Windy

Wind is 19 mph31 km/h from the SW, gusting to 37 mph59 km/h
March 29
10am54°F12°C19 mph31 km/h SWWindy
11am54°F12°C19 mph31 km/h SWWindy
12pm53°F12°C17 mph28 km/h SWWindy
1pm51°F11°C15 mph24 km/h SWMostly Clear
2pm50°F10°C12 mph19 km/h SWMostly Clear
3pm47°F9°C9 mph15 km/h SWPartly Cloudy
4pm46°F8°C8 mph12 km/h SPartly Cloudy
5pm46°F8°C7 mph11 km/h SPartly Cloudy
6pm45°F7°C6 mph10 km/h SPartly Cloudy
7pm44°F7°C6 mph10 km/h SPartly Cloudy
8pm44°F7°C6 mph9 km/h SPartly Cloudy
9pm44°F6°C5 mph8 km/h SPartly Cloudy
DateLowHighWindDayNight
March 2844°F7°C54°F12°C16 mph25 km/h from SWWindyMostly Cloudy
March 2941°F5°C55°F13°C6 mph10 km/h from SMostly CloudyPartly Cloudy
March 3043°F6°C58°F14°C13 mph22 km/h from EMostly CloudyRain
March 3144°F6°C52°F11°C7 mph11 km/h from NWRainDrizzle
April 143°F6°C54°F12°C9 mph15 km/h from SDrizzleRain
April 243°F6°C53°F12°C18 mph30 km/h from WDrizzleMostly Cloudy
April 342°F5°C54°F12°C13 mph21 km/h from SDrizzleDrizzle

Yes

Low of 41°F5°C, High of 55°F13°C
Wind: 6 mph10 km/h
Precipitation: None

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