RIVERSIDE, Calif. -

Much cooler temperatures, light rain and gusty winds are in store for Riverside County starting Wednesday, meteorologists said today.

``A cold low pressure system will develop over the Pacific Northwest (today), then move quickly southward through Central California on Wednesday and through Southern California late Wednesday through early Thursday,'' according to the National Weather Service.

High temperatures in the region will be 15 to 25 degrees below average for the time of year, meaning they'll be in the mid-50s to mid-60s in the valleys, mid-30s to mid-50s in the mountains, the 60s in the upper deserts and in the 70s in the lower deserts, an NWS advisory said.

Rainfall from the system was expected to range from one- to two-tenths of an inch of rainfall in the valleys to a quarter- to three-quarters of an inch in the mountains.

The cold low pressure system was also expected to bring sustained 20 to 30 mile per hour westerly winds to the mountains and deserts, and widespread gusts up to 50 mph. Isolated gusts up to 65 mph were also possible, the NWS said.

Snowfall was possible in the county's highest peaks, though it would be a small amount, if any. The NWS said the snow level would drop to 5,500 to 6,000 feet Wednesday night through early Thursday, with a few inches of snowfall possible above 6,000 feet and around a half-foot above 7,000 feet.