UPDATE 9/19/21 AT 10:00 A.M.
The National Weather Service has upgraded the Fire Weather Watch to a Red Flag Warning which will be in effect from tonight, September 19, at 11PM through Monday, September 20, at 8PM. Dry northerly offshore winds will push into the Napa hills around 11PM Sunday night and then gradually spread over the North Bay hills locally. Dry offshore winds will begin a rapid drying of the atmosphere with humidity values dropping quickly by Monday morning. Continued moderate offshore winds on Monday as humidity values drop into the teens. Offshore winds will ease by sunset Monday night
*Red Flag Warning for North Bay Mountains Tonight (Sunday 9/19) at 11PM through Monday (9/20) at 8PM*
* AFFECTED AREA... Locally, North Bay Mountains. Napa hills that received less than a tenth of an inch of rain will be the areas of biggest concern.
* IMPACTS... Any fire starts would likely see rapid spread due to dry fuels, low humidity and gusty winds in areas that did not receive wetting rains over the last 24 hours.
* TIMING...11 PM Sunday night to 8 PM Monday evening. Initial burst of gusty offshore winds overnight to mid-morning Monday. Drier conditions but lighter winds Monday daytime. Offshore winds ease Monday night with continued poor humidity recovery.
* WINDS... Northeast 10 to 20 mph with gusts up to 40 mph. Local gusts up to 50 mph over the highest peaks.
* RELATIVE HUMIDITY... Initially 30-45% tonight drying to 15-30% on Monday with little or no recovery Monday night.
A Red Flag Warning means warm temperatures, very low humidities, and stronger winds are expected to combine to produce an increased risk of fire danger. Visit srcity.org/WildfireReady and srcity.org/ReadySR for preparedness information.
ORIGINAL MESSAGE 9/17/21
FIRE WEATHER WATCH IN EFFECT FROM SUNDAY (9/19) PM THROUGH TUESDAY (9/21) AM FOR GUSTY OFFSHORE WINDS FOR NORTH AND EAST BAY AREAS OVER 1,000 ft.
The National Weather Service is forecasting fall-like weather this weekend. This weekend’s storm system will bring breezy conditions and a chance of beneficial rain. Then, a rapid shift towards gusty winds and drier conditions will occur from Sunday night through Tuesday that will disproportionately impact the interior North Bay hills and mountains locally above 1000 feet. These drying conditions and gusty offshore winds, in conjunction with near to record dry fuels across the area, will result in an increased risk of critical fire weather concerns for the areas above 1000ft that see light to no rain over the weekend. The amount of rainfall we receive this weekend will like dictate wither of not the NWS upgrades this watch to a red flag warning.
* AFFECTED AREA... North Bay Mountains and East Bay Hills above 1000 feet where the strongest winds, driest fuels, and lowest humidity values are expected.
* TIMING... 11 PM Sunday night to 11 AM Tuesday morning. Initial burst of gusty offshore winds Sunday night to mid-morning Monday. Drier conditions but lighter winds Monday daytime. Second shot of gusty offshore winds and drier conditions Monday night into Tuesday.
* WINDS... North to Northeast 15 to 25 mph with gusts 30 to 40 mph, locally up to 50 mph at the ridge tops. Weaker winds at lower elevations.
* RELATIVE HUMIDITY... Sunday night recoveries 40-60%. Monday minimum daytime humidities 10-20%. Monday night recoveries 25-45%.
* IMPACTS... Any fire starts would likely see rapid spread due to dry fuels, low humidity and gusty winds in areas that do not receive wetting rains over the weekend.
A Fire Weather Watch means that critical fire weather conditions are forecast to occur. Check for later forecasts and possible Red Flag Warnings. Visit srcity.org/WildfireReady and srcity.org/ReadySR for preparedness information.