Yes

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

Why? Because it's quite chilly.
45°F7°C & Cloudy

Wind is 4 mph6 km/h from the S, gusting to 7 mph12 km/h
March 29
8am46°F8°C4 mph7 km/h SCloudy
9am47°F8°C5 mph8 km/h SCloudy
10am47°F8°C6 mph9 km/h SCloudy
11am48°F9°C6 mph10 km/h SCloudy
12pm50°F10°C7 mph11 km/h SECloudy
1pm52°F11°C9 mph14 km/h SEDrizzle
2pm53°F12°C9 mph15 km/h SECloudy
3pm55°F13°C11 mph18 km/h SEDrizzle
4pm55°F13°C13 mph21 km/h SRain
5pm56°F13°C14 mph22 km/h SRain
6pm55°F13°C15 mph24 km/h SRain
7pm55°F13°C16 mph25 km/h SRain
DateLowHighWindDayNight
March 2944°F7°C56°F13°C11 mph18 km/h from SRainDrizzle
March 3047°F8°C58°F14°C7 mph11 km/h from ERainRain
March 3145°F7°C60°F16°C7 mph11 km/h from WPartly CloudyPartly Cloudy
April 145°F7°C62°F17°C5 mph9 km/h from NWClearClear
April 247°F9°C64°F18°C5 mph8 km/h from NWClearMostly Clear
April 349°F9°C59°F15°C8 mph12 km/h from NWMostly CloudyPartly Cloudy
April 446°F8°C54°F12°C15 mph24 km/h from NWPartly CloudyPartly Cloudy

Yes

Low of 46°F8°C, High of 58°F15°C
Wind: 7 mph11 km/h
Precipitation: 62% rain

Support This Page