SAN DIEGO -- Temperatures are expected to be cooler Wednesday, but winds will increase late Wednesday evening and humidity will drop to bring an increased risk of fire danger in San Diego County.
The National Weather Service issued a Red Flag warning that will be in effect from noon Thursday to 6 p.m. Friday for the western valleys and the county mountains.
The weather prompted San Diego Gas & Electric to warn that up to 30,000 people could lose power for precautionary fire danger outages. More than 500,000 people were already affected by similar outages in Northern California Wednesday morning.
Winds blowing to the west could reach 10 mph Wednesday in the western valleys and 30 mph in the mountains.
Those winds will begin blowing east late Thursday -- but remain in the 20-30 mph range -- and gusts could reach 50 mph overnight into Friday, forecasters said. The strongest winds are expected Thursday night through Friday morning.
Daytime humidity will fall to 5-10% Thursday and remain around 5% Friday.
Low humidity will continue into Saturday, but winds will be much weaker by then, according to the NWS.
The threat was deemed marginal Thursday and moderate Friday, according to the Santa Ana Wildfire Threat Index, which means that and "upon ignition, fires may grow rapidly" on Thursday and "fires will be difficult to control" on Friday.
High temperatures Wednesday could reach 75 degrees near the coast and inland, 80 in the western valleys, 78 in the mountains and 98 in the deserts.