The pattern change began Monday when the barometric pressure surrounding the region started to fall gradually. That increase in low pressure is coming from the southwest and the air is flowing north, opposite of many winter low-pressure systems that dip in from the Pacific Northwest. As a result, light but steady rain is expected to start in Monterey County and the Central Coast late Tuesday morning. The rain is expected to reach the region closer to San Francisco sometime Tuesday night, Murdock said.
Rain was expected to return to the Bay Area overnight Monday and could stick around through next week, potentially complicating holiday travel, according to the National Weather Service forecast office in Monterey. The North Bay will welcome the first salvo of showers, the agency said in an area forecast discussion. The wet weather will then spread south to the Peninsula by Tuesday afternoon. Showers are expected to continue into Wednesday.
The Bay Area received rain over four days during the past week, although it was distributed unevenly with the North Bay having more on some days and the South Bay getting wetter later in the week. With at least 10 days of sunny weather expected in the forecast through mid-October, dry conditions are back. And the light rain of the past week wasn't enough to end fire season, experts say.