What Is a Red Flag Warning?
A red flag warning is a critical fire weather alert issued by the NWS when weather conditions are ripe for wildfires. The combination of warm temperatures, low humidity, and strong winds significantly raises the risk of fires igniting and spreading quickly. This alert serves as a caution to residents and local authorities, urging them to take preventive measures and stay vigilant.
Diablo Winds and Fire Risk
Meteorologists are particularly concerned about Diablo winds, the seasonal winds that blow from inland areas such as Nevada and Utah into Northern California. These winds, similar to Southern California’s Santa Ana winds, dry out vegetation, creating ideal conditions for fire ignition and spread. In 2017, Diablo winds contributed to the devastating wine country fires, highlighting the danger posed by such weather patterns.
This week, a small weather system is expected to move through Northern California, bringing a brief chance of rain before giving way to these dangerous winds. Wind gusts in some areas could reach 45 to 55 mph, especially in the Sacramento-San Joaquin Delta. These winds, combined with relative humidity levels as low as 10% to 25%, will create critical fire weather conditions through Saturday.
Areas Covered by the Red Flag Warning
The red flag warning weather impacts a wide geographical area in Northern California. It includes parts of the Sacramento Valley, foothills, and the northern San Joaquin Valley, extending across several counties:
- Sacramento County
- San Joaquin County
- Shasta County
- Butte County
- Tehama County
- Yolo County
- Stanislaus County
- El Dorado County
These counties are at significant risk due to the combination of high winds and dry conditions.
Fire Weather Precautions
Residents are urged to take fire safety precautions during this period of elevated risk. If you’re wondering what is a red flag warning and what to do when one is issued, here are some key safety measures:
- Avoid burning: If you are in an area where burning is allowed, make sure burn barrels are properly covered with a metal lid to prevent embers from escaping.
- Be mindful of cigarette disposal: Throwing cigarettes or matches from a moving vehicle can ignite dry grass, leading to fires.
- Properly extinguish outdoor fires: Always ensure outdoor fires are completely out by drowning them with water and stirring until cold. Never leave a fire unattended.
- Reduce fire hazards at home: During red flag warning periods, avoid activities that can produce sparks, such as mowing dry grass or parking vehicles on dry vegetation.
Local Firefighting Efforts
Firefighters are preparing for increased fire activity, particularly near the Shoe Fire in the Shasta-Trinity National Forest. The fire, which has already burned over 3,400 acres, is expected to produce more smoke and pose additional challenges due to the strong winds.
Fire departments across Northern California, especially in high-risk areas like the East Bay hills and North Bay mountains, are also stepping up their readiness. Many are upstaffing personnel and pre-positioning strike teams in preparation for potential outbreaks.
Power Shutoffs by PG&E
Pacific Gas and Electric (PG&E) is monitoring the weather closely and has announced potential power shutoffs in several counties, including Alameda, Napa, Solano, and Sonoma. These preventive shutoffs aim to reduce the risk of PG&E equipment sparking fires in the dry, windy conditions expected during the red flag fire warning.
Here is a list of the potentially affected counties:
- Thursday, Oct. 17: Alameda, Colusa, Contra Costa, Glenn, Lake, Mendocino, Napa, Shasta, Solano, Sonoma, Tehama and Yolo
- Friday, Oct. 18: Alameda, Alpine, Amador, Butte, Calaveras, Colusa, Contra Costa, El Dorado, Fresno, Glenn, Lake, Madera, Mariposa, Mendocino, Merced, Monterey, Napa, Nevada, Placer, Plumas, San Luis Obispo, Santa Barbara, Shasta, Sierra, Solano, Sonoma, Stanislaus, Tehama, Tuolumne, Yolo
- Saturday, Oct. 19: Alameda, Alpine, Amador, Butte, Calaveras, Colusa, Contra Costa, El Dorado, Fresno, Glenn, Lake, Madera, Mariposa, Mendocino, Merced, Monterey, Napa, Nevada, Placer, Plumas, San Luis Obispo, Santa Barbara, Shasta, Sierra, Solano, Sonoma, Stanislaus, Tehama, Tuolumne, Yolo
PG&E customers in those counties can look up their address online to monitored for a potential shutoff in their local area here.
Weather Outlook and Potential Relief
While temperatures are expected to remain near normal—ranging from the mid-80s in the Valley to 60s and 70s in the foothills—the extreme fire weather should begin to ease by Sunday. Forecasts suggest a cooling trend could bring back onshore winds, reducing fire danger and providing some relief.
However, until conditions improve, the risk remains high, especially in areas prone to dry winds and low humidity. The NWS and local fire authorities continue to emphasize the importance of staying informed, following fire safety protocols, and being prepared to act quickly should a fire threaten your area.
In summary, the red flag fire warning is a critical reminder of the dangers posed by California’s fire season. As winds pick up and humidity drops, the threat of wildfire looms large over the region, and it’s vital for everyone to stay vigilant and prepared.
