Red flag warning issued for Northern California's interior amid forecast of strong winds

Red flag warning issued for Northern California's interior amid forecast of strong winds

1. Red flag warning issued for Northern California's interior as strong winds are forecasted.
2. Northern California’s interior faces red flag warning with strong winds expected.
3. Red flag warning in place for Northern California’s interior due to predicted high winds.
4. Strong winds forecast prompt red flag warning for Northern California’s interior.
5. Will strong winds worsen fire risks in Northern California’s interior under the red flag warning?

A red flag warning has been issued for most of interior Northern California due to the heightened fire risk from high winds and dry conditions, starting Thursday night. The National Weather Service (NWS) announced the warning on Tuesday, upgrading a previous fire weather advisory. This comes as Diablo winds from the north are expected to increase following a small weather system passing through the area. Meteorologists noted that while a brief chance of light rain is possible on Wednesday, the system will create "critical fire weather conditions" through Saturday. “The primary concern is the system’s path into the Great Basin,” said the NWS Sacramento office on Tuesday. “This setup, known as a classic fall ‘Inside Slider’ pattern, will bring strong north to east winds and low daytime humidity through the week’s end.”

DIABLO WINDS EXPECTED TO INCREASE

Diablo winds, similar to the Santa Ana winds in Southern California, are a seasonal autumn phenomenon that carry warm, dry air from Nevada and Utah into California, rapidly drying out vegetation and creating conditions ripe for wildfire spread. The absence of cooling onshore winds from the Bay Area exacerbates these extreme conditions. This was particularly evident in 2017, when a high-pressure system drove dry winds from the Great Basin into the state, fueling the catastrophic wine country fires in Northern California and intensifying the Santa Ana winds that triggered a firestorm in Southern California.

The latest red flag warning will take effect at 11 p.m. Thursday for most of the Sacramento Valley, foothills, and upper San Joaquin Valley, according to forecasters.

**STRONG WINDS AND LOW HUMIDITY EXPECTED**  

Wind gusts in the Valley could reach up to 45 mph, with sustained winds of 15 to 25 mph. Stronger winds are expected in the Sacramento-San Joaquin Delta, where gusts could hit 55 mph and sustained winds will range from 20 to 30 mph. U.S. Forest Service officials also warned that these winds could carry smoke from the Shoe Fire across the Valley. The fire, burning in Shasta-Trinity National Forest since October 9, has consumed 3,420 acres and is 7% contained as of Tuesday.  

“These wind conditions will increase fire activity, leading to more smoke production,” firefighters reported. "Residents and visitors to the forest will likely see and smell smoke, with heavy smoke lingering in the greater Redding and northern state areas for several days."  

Despite the challenging conditions, firefighters emphasized that they remain fully engaged and will continue aggressive efforts to contain the Shoe Fire.

Conditions away from the fire won’t be much better: Humidity levels are expected to drop to between 10% and 25% on Friday and Saturday, with "moderate to poor" overnight conditions offering little moisture recovery. “The combination of gusty winds and low humidity can cause new fires to ignite and existing ones to spread rapidly in size and intensity,” the warning stated. Temperatures in the region are forecasted to remain near normal, with highs in the low to mid-80s in the Valley and 60s to 70s in the foothills. However, long-range forecasts suggest a cooling trend as onshore winds return Sunday, bringing more favorable conditions into next week.

**AREAS COVERED BY THE WARNING**  

The red flag warning applies to the following counties:  

- Amador (below 1,000 feet)  
- Butte (including foothills above 1,000 feet)  
- Calaveras (below 1,000 feet)  
- Colusa  
- El Dorado (below 1,000 feet)  
- Glenn  
- Placer (below 1,000 feet)  
- Sacramento  
- San Joaquin  
- Shasta (from Redding north through Shasta Lake)  
- Solano  
- Stanislaus  
- Sutter  
- Tehama (including foothills above 1,000 feet)  
- Yolo  
- Yuba  

The warning covers fire zones 213, 215, 216, 217, 218, 219, and 266, and remains in effect until 5 p.m. Saturday, with the strongest winds expected on Friday.