Full Notification

National Weather Service has issued a RED FLAG WARNING for EAST BAY HILLS until 11 pm TONIGHT 9/19 thru 8 pm 9/20. ...Red Flag Warning 11 pm Sunday through 8 pm Monday for the North and East Bay hills as well as the East Bay interior valleys....Dry northerly offshore winds will push into the Napa hills around 11 pm Sunday night and then gradually spread over the North and East Bay hills. The initial burst of winds will occur while humidity values remain fairly moist. However, the 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. Little or no humidity recovery Monday night into Tuesday morning but with only light offshore winds.

CAZ507-511-200515-
/O.UPG.KMTR.FW.A.0005.210920T0600Z-210921T1800Z/
/O.NEW.KMTR.FW.W.0006.210920T0600Z-210921T0300Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
946 AM PDT Sun Sep 19 2021

...RED FLAG WARNING IN EFFECT FROM 11 PM THIS EVENING TO 8 PM PDT
MONDAY FOR DRY OFFSHORE WINDS FOR THE NORTH AND EAST BAY HILLS...

The National Weather Service in San Francisco has issued a Red
Flag Warning for dry offshore winds, which is in effect from 11 PM
this evening to 8 PM PDT Monday. The Fire Weather Watch is no
longer in effect.

* AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains and
Fire Weather Zone 511 East Bay Hills and the Diablo Range. The
Napa hills and East Bay hills that received less than a tenth of
an inch of rain will be the areas of biggest concern.

* 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.

* 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.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.