Red Flag Warning in effect until 11 PM Saturday due to high temps. and gusty winds. 
Per Napa County OES -
...Gusty northerly winds coupled with low humidity values Friday Night through Saturday... .Dry northerly flow is forecast to develop over the North Bay during the day Friday with temperatures warming to above seasonal averages. Northeast winds will strengthen Friday night into early Saturday morning with poor relative humidity recoveries followed by even warmer and drier conditions during the day Saturday. The areas of greatest concern will be located in higher terrain of Napa County as well as far eastern Sonoma County. Any fire starts may spread rapidly in these conditions. Avoid activities that may lead to fire ignition, including lawn work, driving on grass, tossing cigarettes, lighting campfires or fireworks, especially Friday night into Saturday afternoon. ...RED FLAG WARNING IN EFFECT FROM 11 PM FRIDAY TO 11 PM PDT SATURDAY FOR GUSTY NORTHERLY WINDS AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONE 507... The National Weather Service in San Francisco has issued a Red Flag Warning, which is in effect from 11 PM Friday to 11 PM PDT Saturday.
* AFFECTED AREA...Fire weather zone 507, especially higher elevations of Napa County and far eastern Sonoma County.
* WIND...Northerly winds of 15 to 30 mph with gusts to 40 mph. Isolated peaks and ridges could experience locally stronger winds, especially Friday night.
* HUMIDITY...Minimum humidity readings of 10 to 20% will be common during the day, with the driest locations dropping into the single digit range during the warmest, driest, windiest times of the day. Overnight humidity recoveries will be poor and less than 30%.
* IMPACTS...Any fires that develop will likely spread rapidly. Outdoor burning or other activities that may lead to fire creation are not recommended.
* AFFECTED AREAS: NORTH BAY MOUNTAINS
Instructions:
A red flag alert means that the critical weather conditions of fire are happening now ... or they will do so shortly. A combination of strong winds ... low relative humidity ... and warm temperatures can contribute to extreme fire behavior.
Address/Location
City of Napa
955 School St
Napa, CA 94559
Contact
Emergency: 9-1-1
Non-emergencies: 707-258-7843