Yes

you do need a jacket based on the weather in Wandsworth, London SW18, UK 1 second ago

Why? Because it's so windy, your hat will probably launch into orbit!
61°F16°C & Mostly Cloudy

Wind is 13 mph21 km/h from the West, gusting to 30 mph48 km/h
May 25
5am61°F16°C14 mph22 km/h WestMostly Cloudy
6am63°F17°C14 mph22 km/h WestMostly Cloudy
7am64°F18°C14 mph22 km/h WestPartly Cloudy
8am66°F19°C14 mph22 km/h WestPartly Cloudy
9am67°F19°C14 mph23 km/h WestPartly Cloudy
10am66°F19°C15 mph24 km/h WestPartly Cloudy
11am66°F19°C15 mph23 km/h WestMostly Cloudy
12pm65°F18°C14 mph23 km/h WestPartly Cloudy
1pm64°F18°C14 mph23 km/h WestMostly Cloudy
2pm62°F17°C14 mph22 km/h WestMostly Cloudy
3pm60°F16°C12 mph20 km/h WestCloudy
4pm58°F15°C12 mph19 km/h WestPartly Cloudy
DateLowHighWindDayNight
May 2454°F12°C67°F19°C13 mph21 km/h from WestMostly CloudyMostly Clear
May 2551°F10°C63°F17°C12 mph19 km/h from SouthwestMostly CloudyDrizzle
May 2655°F13°C65°F18°C13 mph21 km/h from SouthwestDrizzleRain
May 2755°F13°C67°F19°C12 mph19 km/h from WestMostly CloudyMostly Cloudy
May 2853°F12°C71°F22°C11 mph18 km/h from SouthwestDrizzleMostly Cloudy
May 2958°F15°C72°F22°C9 mph15 km/h from WestMostly CloudyPartly Cloudy
May 3056°F13°C70°F21°C7 mph10 km/h from SouthMostly CloudyPartly Cloudy

Yes

Low of 51°F11°C, High of 63°F17°C
Wind: 12 mph19 km/h
Precipitation: 25% rain

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