An unusually early storm will spread rain across Northern California on Wednesday and Thursday, bringing the heaviest precipitation to the North Coast and potentially giving Santa Rosa one of its wettest starts to September in decades.
Rain will reach the North Coast on Wednesday morning and spread inland during the day, arriving in batches through Friday. As much as 2.5 inches may fall in the mountains of Del Norte County, while one-half to three-quarters of an inch is forecast around Humboldt Bay. Northern Mendocino County and other favored coastal and mountain locations could receive one-half inch or more.
Amounts will diminish sharply toward the Bay Area. Up to 0.25 inches could fall in Santa Rosa and the Sonoma valleys, while the North Bay coastal ranges have the best chance of receiving up to an inch. Lighter totals are likely in Napa and Marin counties, with little more than drizzle or spotty light rain expected in San Francisco and elsewhere around the bay.
The storm could deliver one of the most substantial early-September rains in decades. Santa Rosa has not received a quarter-inch during September’s first four days since 2000, while Napa has not recorded even a tenth of an inch during that period since 1940…