Environment & Science

Heat wave to raise Southern California fire danger

In this file photo, U.S. Forest Service firefighters from San Bernardino County watch a firefighting helicopter they requested drop water on a spot fire near the Mount Wilson Observatory in the San Gabriel Mountains on September 21, 2009 in the Angeles National Forest, north of Pasadena, California. Forecasters say a heat wave building across Southern California will elevate fire danger through early next week.
In this file photo, U.S. Forest Service firefighters from San Bernardino County watch a firefighting helicopter they requested drop water on a spot fire near the Mount Wilson Observatory in the San Gabriel Mountains on September 21, 2009 in the Angeles National Forest, north of Pasadena, California. Forecasters say a heat wave building across Southern California will elevate fire danger through early next week.
David McNew/Getty Images

Forecasters say a heat wave building across Southern California will elevate fire danger through early next week.

The National Weather Service says temperatures will edge upward to around 100 degrees in the warmest areas Friday and the peak of the heat wave will extend from Saturday through Monday, with records likely.

Meteorologists say the heat is being generated by an upper-level ridge of high pressure building off the California coast combined with weakening onshore flow. Over the weekend the flow of air will become weakly offshore.

Off the southwest coast of Mexico, meanwhile, Tropical Storm Odile is expected to become a hurricane on Friday and move northwestward along the Baja California peninsula. It's not yet clear if it will be the third such storm to impact Southern California this summer.