Yes

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

Why? Because it's quite chilly.
48°F9°C & Mostly Clear

Wind is 2 mph4 km/h from the N, gusting to 4 mph7 km/h
March 28
11am50°F10°C2 mph3 km/h NWMostly Clear
12pm52°F11°C2 mph3 km/h SWMostly Clear
1pm54°F12°C3 mph5 km/h SWMostly Clear
2pm57°F14°C4 mph6 km/h SWMostly Clear
3pm60°F15°C5 mph8 km/h SWMostly Clear
4pm62°F17°C7 mph11 km/h SWMostly Clear
5pm64°F18°C9 mph14 km/h SWMostly Clear
6pm65°F18°C10 mph16 km/h SWMostly Clear
7pm64°F18°C11 mph18 km/h SWMostly Clear
8pm63°F17°C11 mph18 km/h SWMostly Clear
9pm61°F16°C11 mph17 km/h SWPartly Cloudy
10pm58°F14°C9 mph15 km/h SWMostly Cloudy
DateLowHighWindDayNight
March 2847°F8°C65°F18°C7 mph11 km/h from SWMostly ClearPartly Cloudy
March 2944°F7°C57°F14°C8 mph12 km/h from SWPartly CloudyRain
March 3044°F7°C50°F10°C6 mph10 km/h from SWRainDrizzle
March 3143°F6°C52°F11°C4 mph7 km/h from SERainMostly Cloudy
April 143°F6°C62°F17°C4 mph7 km/h from SWMostly ClearClear
April 248°F9°C72°F22°C5 mph9 km/h from NClearClear
April 355°F13°C77°F25°C4 mph7 km/h from SWClearClear

Yes

Low of 44°F7°C, High of 57°F14°C
Wind: 8 mph12 km/h
Precipitation: None

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