What is a red flag warning?

A Red Flag Warning means warm temperatures, very low humidities, and strong winds are expected to combine to produce an increased risk of fire danger. The National Weather Service is in charge of issuing the warnings when forecasted weather is expected to meet the criteria.

What is required to issue a Red Flag Warning?

The conditions that must exist include all three of the following:

• 10 hour fuel moisture of 8% or less. This parameter describes how much water is held by small vegetation such as grass, leaves, and mulch that take only about ten hours to respond to changes in dry/wet conditions.
• Relative humidity of less than 25% for several hours. RH depicts how much water is in the air, relative to the temperature of the air.
• Winds 20 feet above the ground of at least 15 mph for several hours

Red Flag Warning vs Fire Weather Watch

A Red Flag Warning is issued for weather events which may result in extreme fire behavior that will occur within 24 hours. A Fire Weather Watch is issued when weather conditions could exist in the next 12-72 hours. A Red Flag Warning is the highest alert. During these times extreme caution is urged by all residents because a simple spark can cause a major wildfire. A Fire Weather Watch is one level below a warning, but fire danger is still high.

Red Flag Warning Safety Tips

Equipment

• Avoid using lawn mowers on dry vegetation
• Follow all local fire restrictions on the use of chainsaws, mowers, and other equipment during high risk times.

Outdoor fires

• Be mindful of any burn bans in your area and obtain a permit if needed.
• Extinguish outdoor fires properly, never leave them unattended. Always drown them with plenty of water.
• Soak ashes and charcoal in water and dispose of them in a metal can. These materials can reignite days after a fire or BBQ is extinguished.
• Report unattended outdoor fires immediately to 911.

Property

• Keep your lawn green and mowed all season.
• Create at least 100 feet of defensible space around your home by removing leaves, weeds, brush, firewood, and other flammables. Make sure to clean roof and gutters too.
• Make sure access roads to your property are cleared and properly labeled.

Vehicles

• Do not throw cigarettes or matches out of a vehicle. They can ignite grass on the side of the road and start a wildfire. 
• Do not pull your vehicle over in dry grass.
• Ensure that trailer chains don't drag on the ground.

Active Red Flag Warnings

Current or forecasted red flag warning areas are highlighted in red. For more information about the warning, click on the red shading on the map.

Red Flag Warnings for the San Ramon Valley

Red Flag Warnings for California