SAN FRANCISCO (CBS SF/KPIX) – High fire danger during the month of October brings memories of devastating Bay Area wildfires and has fire officials urging residents to exercise serious safety precautions.

Gusty offshore winds and dry conditions prompted the National Weather Service Saturday to issue a Red Flag warning for critical fire conditions this weekend in the Bay Area.

The warning will be in effect Saturday evening through Monday morning, across North Bay mountains, the East Bay hills and the Diablo Range.

Cal Fire issued safety tips to Bay Area residents affected by the warning.

“Any source of ignition to any type of fuel bed or receptive brush – a fire will – its not if – it will spread rapidly with a Red Flag condition,” said Mike Moller, Cal Fire’s Deputy Director.

Eleven of the most deadly wildfires in the Bay Area sparked in October.

The devastating Oakland Firestorm of 1991 was in October.

Last year, Sonoma, Napa and Mendocino counties were torched by a firestorm ignited in Red Flag conditions in October.

Saturday, there was plenty of visible tinder dry, sun bleached grass in the East Bay Hills.

Contra Costa County Fire Marshal Robert Marshall says the low autumn humidity combined with high winds and hot days is a grave concern.

“The big thing that we’re concerned about at this point is the lighter fuels have had all summer to bake. It’s been a hot summer and a dry summer and a very windy summer – which just reduces the fuel moisture,” said Marshall. “But now, what we worry about is the larger fuels, trees don’t have a lot of moisture because it’s been a long time since they’ve received rain. Those are the things that make fires much, much bigger than they would’ve been otherwise.”

Marshall says while the urge to give your house defensible space is good, Red Flag days are not the time to trim on your property.

“If you have not already started to cut your weeds, it’s too late,” said Marshall. “Don’t do that, because that can actually cause a fire, as well. You have to wait until the humidity is higher.”

Moller of Cal Fire says if there is any lesson to be gleaned from the Tubbs Fire destruction in Santa Rosa, it’s to be hyper-vigilant on Red Flag days.

“You need to treat it like it’s a hurricane or tornado coming.”

The greatest threat is at elevations above 1,000 feet in Napa County and eastern Sonoma County, where the driest conditions and strongest winds are most likely, according to the weather service.

Northeast winds are forecast to be from 20 to 35 mph with gusts up to 60 mph in some locations.

Cal Fire also said residents should not drive vehicles over dry grass, make sure cigarettes are properly extinguished and never burn debris like leaves and branches on Red Flag days.

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