California and the US West are facing a burst of summer-like heat in early October, boosting electricity demand and raising the risk of wildfires. The high temperature in downtown Los Angeles is forecast to hit 90F Thursday and climb as high as 98F through the weekend, the National Weather Service said. An extreme heat watch is in effect just inland from Los Angeles and San Diego.

"It is warm over a lot of the West, but from an excessive heat standpoint it is confined to Southern California," said Marc Chenard, a senior branch forecaster. The heat has prompted California ISO to preserve power supplies. Dry offshore winds may increase fire danger.

California ISO expects demand to peak at 43.2 gigawatts on Oct. 6, higher than the earlier estimate of 37.9 gigawatts. Temperatures may stay 8F to 15F above normal through Oct. 14. Overnight temperatures will remain elevated.

David Acuña of Cal Fire said conditions can make vegetation more susceptible to sparks. Through Sept. 28, 5,701 wildfires burned 328,950 acres this year, fewer than the five-year average. The state has hired more firefighters and bought more equipment.