* WHAT...South winds 20 to 30 mph with gusts up to 50 mph.

* WHERE...San Francisco, Marin Coastal Range, Sonoma Coastal Range, North Bay Interior Mountains, North Bay Interior Valleys, San Francisco Bay Shoreline, San Francisco Peninsula Coast

* WHEN...Until 6 AM PST Thursday.

* IMPACTS...Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result.

* WHAT...Large breaking waves between 14 to 19 ft along southwest facing beaches and between 19 to 22 ft along well exposed west facing beaches.

* WHERE...San Francisco, Coastal North Bay Including Point Reyes National Seashore, San Francisco Peninsula Coast and Southern Monterey Bay and Big Sur Coast Counties.

* WHEN...Until 6 AM PST Friday.

* IMPACTS...Dangerous swimming and surfing conditions and localized beach erosion. Large waves can sweep across the beach without warning, pulling people into the sea from rocks, jetties and beaches. Sudden immersion in cold water can result in cold water shock even for the most experienced swimmers. Cold water shock can result in dramatic changes in breathing, heart rate and blood pressure, greatly increasing the risk of drowning in rough open waters.