Yes

you do need a jacket based on the weather in San Francisco, CA 94105, USA 1 second ago

Why? Because it's not very warm out.
54°F12°C & Mostly Clear

Wind is 6 mph10 km/h from the W, gusting to 11 mph17 km/h
March 28
1pm54°F12°C7 mph10 km/h WPartly Cloudy
2pm55°F13°C7 mph11 km/h WPartly Cloudy
3pm56°F14°C8 mph13 km/h WPartly Cloudy
4pm57°F14°C9 mph15 km/h WMostly Cloudy
5pm57°F14°C9 mph15 km/h WPartly Cloudy
6pm57°F14°C10 mph16 km/h WPartly Cloudy
7pm57°F14°C10 mph17 km/h WMostly Cloudy
8pm56°F13°C11 mph17 km/h WMostly Cloudy
9pm55°F13°C11 mph17 km/h WCloudy
10pm53°F12°C10 mph16 km/h WCloudy
11pm53°F11°C8 mph13 km/h WCloudy
March 29
12am52°F11°C7 mph11 km/h WCloudy
DateLowHighWindDayNight
March 2851°F11°C58°F14°C9 mph14 km/h from WPartly CloudyDrizzle
March 2949°F9°C53°F12°C15 mph23 km/h from SERainRain
March 3048°F9°C57°F14°C9 mph15 km/h from NERainMostly Cloudy
March 3148°F9°C61°F16°C5 mph8 km/h from WPartly CloudyMostly Clear
April 149°F10°C63°F17°C5 mph8 km/h from WMostly ClearMostly Clear
April 251°F11°C63°F17°C5 mph9 km/h from SWMostly ClearPartly Cloudy
April 351°F11°C62°F17°C6 mph10 km/h from WPartly CloudyPartly Cloudy

Yes

Low of 49°F10°C, High of 54°F12°C
Wind: 15 mph23 km/h
Precipitation: 78% rain

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