Yes

you do need a jacket based on the weather in Harpenden AL5, UK 1 minute ago

Why? Because it's so windy, you’re practically horizontal just trying to walk!
61°F16°C & Mostly Cloudy

Wind is 13 mph21 km/h from the West, gusting to 25 mph41 km/h
June 6
9am62°F16°C13 mph22 km/h WestMostly Cloudy
10am62°F17°C13 mph21 km/h WestMostly Cloudy
11am62°F17°C13 mph21 km/h WestCloudy
12pm62°F17°C13 mph21 km/h WestMostly Cloudy
1pm61°F16°C12 mph20 km/h WestMostly Cloudy
2pm59°F15°C11 mph18 km/h WestCloudy
3pm58°F14°C9 mph15 km/h WestCloudy
4pm56°F13°C8 mph12 km/h SouthwestCloudy
5pm54°F12°C6 mph10 km/h SouthwestCloudy
6pm53°F12°C6 mph9 km/h SouthwestCloudy
7pm52°F11°C6 mph10 km/h SouthwestCloudy
8pm51°F11°C5 mph9 km/h SouthwestCloudy
DateLowHighWindDayNight
June 550°F10°C63°F17°C11 mph18 km/h from WestDrizzleDrizzle
June 649°F9°C61°F16°C11 mph18 km/h from WestDrizzleDrizzle
June 745°F7°C62°F16°C13 mph21 km/h from WestPartly CloudyMostly Clear
June 847°F9°C68°F20°C8 mph13 km/h from WestPartly CloudyPartly Cloudy
June 950°F10°C71°F22°C8 mph13 km/h from WestPartly CloudyMostly Clear
June 1053°F12°C76°F25°C7 mph12 km/h from SoutheastPartly CloudyPartly Cloudy
June 1159°F15°C77°F25°C9 mph14 km/h from SoutheastDrizzlePartly Cloudy

Yes

Low of 49°F10°C, High of 61°F16°C
Wind: 11 mph18 km/h
Precipitation: 67% rain

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