RIVERSIDE, Calif. -

Strong winds and low humidity will combine today to create a heightened risk of wildfire in the valleys of Riverside County, National Weather Service forecasters said.

The agency scheduled a red flag warning for the valleys from 9 this morning to 5 p.m. Friday, saying a moderate Santa Ana wind event was occurring.

The Coachella Valley, where northeast winds of between 15 and 25 miles per hour were expected this morning, was not affected by the red flag warning.

During the warning, sustained northeast winds of 20 to 30 mph were expected to gust up to 45 mph, and the lowest daytime humidity was expected to be from 5 to 15 percent.

In addition to the red flag warning for the valleys, wind advisories were in effect today for the valleys and the mountains, until 2 p.m.

The strongest winds -- gusting up to 45 mph -- will be near mountain ridge tops as well as through and below favored passes and canyons, according to the weather service.

"The winds will be make driving difficult, especially for motorists with high profile vehicles," an NWS advisory said. "Secure loose yard furniture, tents, umbrellas and trash cans, as these items may blow away."