Gusty winds, warm weather and low relative humidity are expected to raise the risk of wildfires starting Monday in San Diego County's mountains and inland valleys, meteorologists said Saturday.
A National Weather Service Red Flag Warning was scheduled to go into effect at 3 a.m. Monday and extend until 6 p.m. Wednesday for valley and mountain areas including the Palomar and Descanso ranger districts of the Cleveland National Forest.
"A strong ridge of high pressure aloft and at the surface over the Great Basin will result in Santa Ana conditions over Southern California much of next week,'' the warning stated. "Very dry air, much above normal temperatures and periods of strong, gusty winds will result in critical fire weather conditions at times Monday though Wednesday.''
NWS forecasters said the lack of rainfall this winter had further dried vegetation well beyond what was normal for this time of year in many areas.
East to northeast winds of 20 to 30 mph with gusts of up to 50 mph and isolated gusts of up to 60 mph are likely in wind-prone spots along San Diego County's coastal mountain slopes and foothills, according to the NWS. The winds are expected to begin speeding up Sunday night with strongest winds Monday and Tuesday, but they should weaken Wednesday.
Afternoon highs during the warning period are expected to be in the 80s, forecasters said. The warm and dry weather was expected to further dry fuels through Friday and continue to raise the wildfire risk.
The NWS said relative humidity would fall into the teens Sunday night at higher elevations, which would then spread to the valleys Monday morning.
"A combination of strong winds, low relative humidity, above normal temperatures and very low fuel moisture will contribute to extreme fire behavior,'' the NWS said.