When will California heat wave end?

Record high temperatures hit California - north and south - prompting concern over energy use and wildfires. When will it cool down?

An autumn heat wave that is roasting California is expected to reach its peak on Saturday, raising concerns about wildfires and power outages.

As high temperatures were ranging from the low 100s in Southern California to the 90s in the normally more temperate San Francisco Bay Area on Friday, National Weather Service forecasters warned that some high-temperature records could fall Saturday.

They said LA's Woodland Hills neighborhood could surpass 108 degrees.

The National Weather Service says that relief from the heat in the Los Angeles area won't come until Monday or Tuesday: 

Today will be the hottest day of this current heatwave, especially across the coastal valleys and inland coastal areas. The upper level ridge will persist over California today. 

For Sunday, there will be some cooling across coastal areas, especially near the beaches as the afternoon sea breeze kicksIn earlier...With high temps near the beaches lowering 6 to 10 degrees to between the mid 70s and mid 80s. Inland areas will be down only a few degrees with most valley locations remaining in the lower 100s...But closer to 100 degrees.

Strong high pressure aloft and weak offshore [air] flow will persist over the forecast area keeping much of  Southern California very hot and dry through this weekend and into early next week. Increasing onshore flow will bring cooling to the forecast area early next week, with more significant cooling by Tuesday and Wednesday.

A high-pressure system extending over the western part of the country, along with Santa Ana winds that blow across deserts and down mountain canyons before arriving in Southern California, are generating the sweltering conditions.

By mid-afternoon Friday, it was 99 degrees in Long Beach, the same as the temperature in Death Valley, California, which calls itself the hottest place on the planet.

The hot temperatures, dry and windy conditions are triggering warnings of high fire danger across the state.

The U.S. Forest Service has implemented 24-hour firefighter staffing. The Los Angeles County Fire Department has beefed up many of its firefighting crews from three to four people and stationed extra equipment in strategic locations.

"We've got wind, heat, the perfect combination, everything in alignment for a potential brushfire," fire Capt. Rich Moody said Friday as he and his crew patrolled a Southern California hillside.

Meanwhile, the Los Angeles Department of Water and Power is urging people to set thermostats at 78 degrees.