Yes

you do need a jacket based on the weather in Winchester, UK 6 minutes ago

Why? Because it's so windy, your hat will probably launch into orbit!
63°F17°C & Windy

Wind is 18 mph29 km/h from the Southwest, gusting to 30 mph49 km/h
September 17
6am64°F18°C19 mph30 km/h SouthwestWindy
7am65°F18°C20 mph32 km/h SouthwestWindy
8am66°F19°C20 mph32 km/h SouthwestWindy
9am67°F19°C19 mph30 km/h SouthwestWindy
10am67°F19°C18 mph29 km/h SouthwestDrizzle
11am66°F19°C17 mph27 km/h SouthwestDrizzle
12pm66°F19°C16 mph26 km/h SouthwestDrizzle
1pm65°F18°C15 mph25 km/h SouthwestWindy
2pm64°F18°C15 mph23 km/h SouthwestCloudy
3pm64°F18°C14 mph23 km/h SouthwestCloudy
4pm63°F17°C13 mph22 km/h SouthwestCloudy
5pm63°F17°C13 mph21 km/h SouthwestCloudy
DateLowHighWindDayNight
September 1655°F13°C67°F19°C17 mph27 km/h from SouthwestDrizzleDrizzle
September 1761°F16°C69°F20°C15 mph24 km/h from SouthwestCloudyMostly Cloudy
September 1859°F15°C72°F22°C10 mph16 km/h from SouthPartly CloudyMostly Cloudy
September 1956°F13°C68°F20°C12 mph19 km/h from SouthwestDrizzleDrizzle
September 2047°F8°C57°F14°C13 mph22 km/h from NorthwestDrizzleDrizzle
September 2145°F7°C60°F16°C15 mph25 km/h from NorthWindyMostly Clear
September 2245°F7°C59°F15°C13 mph22 km/h from NorthRainDrizzle

No

Low of 62°F17°C, High of 69°F21°C
Wind: 15 mph24 km/h
Precipitation: 11% rain

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