A southerly wind overnight pushed smoke from a wildfire at Camp Pendleton throughout Orange County, where residents as far north as Huntington Beach reported smelling a burning odor.

The fire began at 11:45 p.m. and burned 81 acres of vegetation at the San Mateo helicopter landing zone. The cause of the fire remains under investigation.

Officials with the Air Quality Management District in Diamond Bar recorded a small rise in air pollution at the Anaheim monitoring station early Wednesday. By mid-afternoon, air quality returned to a good-to-moderate range, said Sam Atwood, spokesman for the district.

Cities including Newport Beach and Laguna Beach tweeted that air quality had been affected locally.

That smoky smell is coming from a vegetation fire at Camp Pendleton. https://t.co/wUureYMsVD — CityofNewportBeach (@newportbeachgov) August 16, 2017

“HB residents may notice a smell of smoke and haze this morning from a brush fire burning in South Orange County at Camp Pendleton,” tweeted the Huntington Beach Fire Department.