South Bay getting more March rain, but lags behind North Bay rainfall totals
There have been some solid rainfall totals this month across the South Bay, with drier-than-normal conditions across the North Bay.
Storm systems, or atmospheric rivers, in March, have been tracking farther south than in previous months, bringing San Jose above-average precipitation so far this month. Even though North Bay communities, like Santa Rosa, have seen rain basically every day for the last five days, it's been light rain, keeping below-average precipitation in place across the area.
San Francisco is just slightly below average for precipitation.
As a season, however, rainfall departure is completely flip-flopped.
San Jose is more than 3" below average since Oct. 1, 2024, along with much of the South Bay and inland East Bay. Santa Rosa and other North Bay communities may have been relatively dry this March, but for the rainy season as a whole, they are well above average.
In fact, many locations are around a foot above average for the season. So, why is the North Bay so much wetter than the South Bay when it comes to rainfall departure?
It can all be traced back to Nov. 19-23, 2024 when a huge atmospheric river impacted the Bay Area. It stalled over the North Bay, bringing constant streams of heavy rain while the southern half of the Bay Area barely got wet.
This atmospheric river cut the Bay Area in half in terms of rainfall departure — above average north and below average south. And it was so significant that the rainfall departure was still cut in half through late March.
So again, even though this March has been relatively wetter across the South Bay compared to the North Bay, this rainy season as a whole has seen well below-average rain south and above-average rain north thanks to the November 2024 atmospheric river.
