Residents of two California towns were given mandatory evacuation orders on Thursday as a burgeoning wildfire swept through drought-parched mountains and aircraft battling the blaze could not take off after a drone was spotted in the area, officials said.The fire in the mountains of San Bernardino County east of Los Angeles was among scores of wildfires raging along the US West Coast, from Alaska through California, in areas hit by drought and suffering record-low snowpack.In Idaho, officials on Thursday issued a health advisory tied to extreme heat, as weather forecasters predicted record-breaking highs. The northern end of the Sacramento Valley in California was also unusually hot with 111 degrees Fahrenheit (43.9 Celsius) reported in Redding Thursday afternoon.In Southern California, firefighters were losing ground to the long-burning San Bernardino County blaze, which swelled to 23,199 acres (9,388 hectares) by Thursday in the face of gusting winds, according to fire-tracking website InciWeb, which pulls information from multiple agencies.The blaze, now nine days old, prompted evacuation orders late on Wednesday of two towns and voluntary evacuation of a third as containment dropped to 21 percent. The fire had been about one-third contained the day before.Authorities did not say how many people were ordered to leave but some 7,000 structures were threatened in the areas evacuated. Not all threatened structures are residences.Roadways and campgrounds remain closed and about 360 campers were sent home from the Lake Williams Area on Wednesday."Weather will remain warm and dry over the fire with gusty west winds over the next few days," according to InciWeb, even though temperatures were expected to cool in the next several days.Weather was not the only hurdle. Nearly a dozen firefighting aircraft were grounded after a drone was spotted in the area.In Los Angeles County, roughly 1,000 residents in Santa Clarita were ordered from their homes late on Wednesday as a hard-charging fire spread across some 350 acres (142 hectares) in a matter of hours, the county fire department said.Those evacuation orders were lifted on Wednesday night and the fire was about 60 percent contained by Thursday morning, the department said.In southern Oregon, firefighters had contained 60 percent of a 5,341-acre (2,161-hectare) fire in Cave Junction that has closed forest but not damaged property.