Rain and clearer air are on the way to the San Francisco Bay Area this week after a recent dry spell and smoggy conditions.
Powerful king tides are also expected this week, which raises the risk of coastal flooding.
While some offshore Diablo winds provided minor air circulation in the East Bay, the region has experienced a bout of poor air quality. The government’s AirNow map showed elevated air-quality readings Wednesday morning for San Francisco and many Bay Area cities.
Relief is expected starting tonight as the first of multiple storms moves into the North Bay, with up to an inch of rain forecast for northern Sonoma County overnight. San Francisco could see around half an inch of precipitation through Thursday morning.
A stronger system arriving Friday will bring widespread rain through Saturday, along with significant wind that may prompt advisories.
The storms will help force out the persistent hazy conditions residents have noticed over the past week. The limited air movement was partly due to minimal upper-level atmospheric activity, National Weather Service meteorologist Brayden Murdock told The Standard.
“We haven’t had much in the way of upper-level movement, so that allowed things to kind of stay pretty calm at the surface as well,” Murdock said.
The Bay Area Air Quality Management District issued a Spare the Air alert Sunday, when moderate air conditions covered the greater Bay Area, due in part to agricultural smoke drifting from the Central Valley.
The weather service is also monitoring king tides — the highest and lowest tides of the year — which could affect coastal flooding and river drainage during the wet weather.
“When we see king tides, then we have rivers flowing pretty well that could cause some extra localized flooding during the high tides,” Murdock explained. “But then during the low tides, it actually helps clear out the rivers sooner.”
San Francisco residents remain wary of flood risks following recent storms that overwhelmed street drains in several neighborhoods. Weather officials expect to issue detailed king tide advisories later Wednesday.
A third system, forecast for early next week, appears focused on Northern California, with less impact expected for the Bay Area.