Spare the Air alert for Bay; hot, hazy weekend ahead

Hazy skies were expected over the Bay Area on Friday and Saturday as winds push smoke from Northern California wildfires into the region, the National Weather Service said.

Regional air quality officials on Friday issued a Spare the Air alert for Friday and Saturday, indicating that concentrations of particulate matter pollution and ozone were expected to be unhealthy, especially for young children, seniors, and those with respiratory and heart conditions.

Wildfire smoke that was previously forecast to stay in higher elevations began drifting to lower elevations near the surface on Friday, said Ralph Borrmann, a spokesperson with the Bay Area Air Quality Management

District.

Inland regions in the North and East Bay were expected to be most vulnerable to deteriorating air quality. As of Friday noon, BAAQMD air quality readings showed air was unhealthy for sensitive groups in Concord, Livermore and Pleasanton. The rest of the Bay Area was experiencing moderate air quality.

Dry north winds carrying wildfire smoke into the Bay Area were also expected to lead to a warm-up as high pressure builds through Saturday. Highs approaching 100 to 105 degrees were expected in interior parts of the Bay Area — above normal but not nearing record territory, which the weather service said was the 105110 degree range. However, onshore flow was expected to keep temperatures along and nearer the coast lower. Highs were expected to reach the high 70s to low 80s in San Francisco and the mid-90s in San Jose.

A late sea breeze by Sunday afternoon was forecast to bring cooling to the coast and bay portions of the region, but was not expected to reach interior areas until Monday, when temperatures were expected to cool back to near normal.

Smoke from a number of wildfires burning in Northern California has had a much more severe impact on regions north and east of the Bay Area. Air quality levels ranged from unhealthy to hazardous in Redding and east toward Sacramento and the Lake Tahoe basin, said Matt Mehle, a meteorologist with the National Weather Service.

The Caldor Fire east of Sacramento has been suffocating Reno and Tahoe, Mehle said. The lack of strong winds in the Tahoe basin has meant that wildfire smoke has settled there, blocking the sun and cooling down temperatures into the 80s, Mehle added.

A red flag warning indicating critical fire weather conditions went into effect for northern and central parts of the Sacramento Valley and surrounding foothills at 5 a.m. Friday due to low humidity and the potential for 35-mph wind gusts, Mehle said. The warning was set to expire Saturday at 11 a.m.

The trifecta of hot temperatures, strong winds and low humidity means ripe conditions for wildfires to start and expand, officials said.