SAN DIEGO -- The first Santa Ana winds of the season arrived Monday, with the potential to blast parts of San Diego County with gusts of up to 50 miles per hour and increase fire risk, the National Weather Service said Sunday.
A Red Flag Warning for most of the county will go into effect 8 a.m. Monday and remain in effect through 10 a.m. Tuesday. Areas that faced particularly dangerous conditions included the Palomar and Descanso ranger districts of the Cleveland National Forest.
Northeast winds of 15 to 30 mile per hour were expected Monday morning through Tuesday morning, with gusts of 45 to 50 miles per hour, according to the NWS.
At 7:45 a.m., a California Highway Patrol officer requested a wind advisory go into effect on Interstate 8 from Alpine to San Diego County's eastern barrier with Imperial County. The officer said high-profile vehicles should avoid that stretch of the freeway.
Humidity levels were predicted to fall to between 8 and 12 percent late Monday morning through early Monday evening. On Tuesday, humidity is forecast to remain between 10 and 15 percent.
High temperatures Monday were forecast to be 80 to 90 degrees in the western valleys and foothills, 68 to 77 in the mountains and 84 to 89 in the deserts.
The high temperatures, strong winds and low humidity was expected to create critical fire weather conditions for valleys and coastal foothills throughout San Diego County, according to the NWS forecast. Any fires that develop will likely spread "rapidly with extreme behavior," the NWS said.
U.S. Forest Service officials listed the threat of a Santa Ana-driven wildfire as only marginal Monday across San Diego County, but any wildfire that breaks out "may grow rapidly," according to the Santa Ana Wildfire Threat Index.
The threat was high in Los Angeles and Ventura counties, meaning that potential fires in those regions "will grow very rapidly, will burn intensely, and will be very difficult to control." In Riverside and Orange County, the threat was moderate, meaning potential fires "will grow rapidly and will be difficult to control."
Winds will weaken Tuesday afternoon with humidity beginning to rise in inland areas on Wednesday, the NWS said.
Because of the increased fire danger Monday, the San Diego Fire-Rescue Department put five extra brush engines, two extra water tenders and more than 20 extra firefighters on duty to help battle any potential wildfires.