Temperatures are climbing past 100 degrees across inland Los Angeles County, with the National Weather Service warning that hot, dry conditions are raising the risk of fast-moving wildfires through at least Thursday evening.

A heat advisory issued by the NWS Los Angeles/Oxnard office remains in effect through 8 p.m. Thursday, Aug. 20, covering the San Fernando Valley, San Gabriel Valley, Santa Clarita Valley, Antelope Valley and the Western San Gabriel Mountains, according to The Eastsider. Wednesday and Thursday are expected to bring peak heat.

Woodland Hills and Santa Clarita could top out at 103 degrees Thursday. Palmdale is forecast to hit 101, Burbank 98 and downtown LA up to 91. Pasadena and Van Nuys should reach the upper 90s. Those highs run 4 to 8 degrees above normal for mid-August.

Coastal areas will stay in the 70s.

Fire danger rising

The NWS warned the heat wave will produce elevated risk for large, plume-dominated fire behavior as humidity drops to 10% to 20% across interior areas Wednesday through Friday, according to Patch. Gusty north-to-northwest winds of 20 to 35 mph are expected overnight in the interior mountains, particularly near the Grapevine.

NWS meteorologist Rich Thompson told the Los Angeles Times on Aug. 17 that while the region saw more extreme heat events earlier this summer, this round will be noticeable though not historic. "It's going to be a decent bit of heat," Thompson said.

No overnight relief

A strong inversion and warmer-than-normal sea surface temperatures are keeping nighttime lows elevated. Valley and coastal locations may only cool to the upper 60s or lower 70s overnight, while some foothill and mountain communities could stay above 80 degrees after dark.

The NWS said the advisory may need to be extended into Friday, though forecasters noted considerable uncertainty about the timing. Current forecasts show above-normal temperatures continuing through the weekend and into the following week.

What residents should do

The Los Angeles County Department of Public Health and the LA County Office of Emergency Management both issued alerts urging residents to take precautions. Health officials advise drinking plenty of fluids, staying in air-conditioned spaces during peak afternoon heat and checking on neighbors, especially elderly residents and those without air conditioning.

Officials stressed that children and pets should never be left in parked vehicles, even briefly. Temperatures inside a car can reach deadly levels within minutes.

The heat risk is particularly acute for people without adequate cooling or hydration, the NWS said.

Cooling centers across LA County are listed at ready.lacounty.gov/heat.