Two weather systems dropping down from the Pacific Northwest are expected to sweep Northern California this week, cranking up high winds, pushing down temperatures and even delivering light rain.
In a state that’s water-starved after two consecutive dry winters, this forecast is good news, but experts said the conditions are unlikely to have any impact on reversing the catastrophic drought conditions or significantly stalling the arrival of peak wildfire season.
“Unfortunately, no. The upcoming period of cooler weather and some light showers across far Northern California (north of the Bay Area) will not substantively affect the extreme long-term drought in Northern California, which is expected to further worsen over the upcoming dry season,” said UCLA climatologist Daniel Swainy, who writes about weather, climate and regional change in California and beyond on his Weather West site. “The earliest California could potentially see meaningful drought relief would be next winter — so there’s still all of summer and autumn to get through first.”
The rain is most likely to be light and scattered and fall in the northernmost reaches of the state, with chances running from mid-week into the weekend.
On Friday and Saturday, there’s up to an 80% chance of showers in Humboldt County and 15% to 20% in the North Bay, according to the National Weather Service. Rain is highly unlikely south of the Golden Gate.
While the rain may moisten the landscape, measurable amounts are unlikely to make it into Northern California’s reservoirs, which are below half capacity.
“It’s going to have zero impact on drought,” said Jan Null, who runs private forecasting service Golden Gate Weather Services. “This is the time our Mediterranean climate is defined by the fact we have a drought every summer. Any rain we get, it’s going to evaporate and get soaked right into the landscape.”
Temperatures are also expected to drop several degrees below normal across Northern California this week. Afternoon highs around the Bay Area will be up to 15 degrees below normal in inland valleys and 5 degrees below average on the coast, according to the weather service. The chilliest spots could see overnight lows drop into the 30s.
The combination of rain and cool temperatures may delay the arrival of peak wildfire season in Northern California, but it will likely be insignificant.
“It may help temporarily tamp down wildfire conditions across the northern quarter of the state (for a week or so, perhaps), but is unlikely to have a lasting influence beyond that,” Swain said.
Craig Clements, a professor and director of the Wildfire Interdisciplinary Research Center at San Jose State University, echoed Swain’s comments and expressed concerns around the winds kicking up.
“The cooling trend will help some. Regarding the rain, it depends on the amount,” said Clements, noting that the rain is unlikely to impact the water content of plants and make them less flammable. “The issue now is that strong winds this week, even though it’s cooler, are problematic with potential grass fires.”