Spare the Air alert returns following a two-day break

The region’s break from smoky weather proved to be a brief one, and Bay Area residents must return to using caution in dirty air again this weekend, officials said Friday.

The area’s 31st Spare the Air alert this year was announced Friday, and it is in effect for Saturday. The alert by the Bay Area Air Quality Management District bans wood-burning and encourages residents to reduce their carbon emissions.

The alert comes after two straight days of good air throughout the region that followed a record streak of 30 consecutive Spare the Air days. That run obliterated the old mark of 14 consecutive alerts set during the 2018 Camp Fire in Paradise and equaled the number of Spare the Air days combined the previous four years.

During the streak, the Bay Area was choked by smoky, ashy air. On one day last week, smoke blown down from the fires and trapped in the marine layer cast a dark orange pall over the region and kept street lamp and car headlights on through the day.

The air does not figure to be so bad this weekend, but air quality forecasters said smoke is trailing behind a cold front that moved through the region Friday and left it with air quality index readings below 50.

That smoke is close to the ground, according to forecasters and, combined with a wind flow developing in the Sacramento Valley, could lift the air quality readings into areas that are moderately unhealthy and unhealthy for those with breathing or underlying conditions.

Those conditions could get gradually worse heading into Sunday, forecasters said. The air is expected to be the worst in the East Bay and North Bay, according to forecasters.

The smoke is being generated by the August Complex fires in Mendocino and Humboldt counties and the North fires, which are burning in Plumas and Butte counties. The two fires have combined to burn more than 1.1 million acres, according to the California Department of Forestry and Fire Protection.