* WHAT. Dangerously hot conditions with high temperatures of 98 to 108 degrees common. Warm overnight lows of 75 to 85 degrees are expected in the lower mountains and foothills. * WHERE. Most mountains and valley areas. * WHEN. From 10 AM this morning to 8 PM PDT Monday. * IMPACTS. There is a high risk for dangerous heat illness for anyone, especially for the very young, the very old, those without air conditioning, and those active outdoors. * ADDITIONAL DETAILS. It will be very dangerous to perform strenuous activities during the late morning through early evening hours this weekend. Use extreme caution when hiking or biking anywhere in the warned area, including in the popular Santa Monica Mountains.

Dense fog is currently being observed tonight and will likely continue through at least Monday morning. Dense Fog will be the most widespread during the evening through the morning hours. Mariners should be prepared for abrupt visibility changes down to one nautical mile or less. Reduce speeds and be on the lookout for exposed rocks and other vessels, including large ships in the shipping lanes. Use radar or GPS navigation if available, and consider remaining in harbor if such equipment is unavailable.