Yes

Based on the weather in Napa, California, United States Of America as of September 30, 2016 9:49pm local time

Why? Because it's pretty chilly.
Current Conditions
Clear
Temp: 58.1°F14.5°C
Wind: 3.8 MPH6.1 KPH
Precipitation: None

Next 2 hours: Yes

Next 4 hours: Yes

Next 8 hours: Yes