Here are SF Bay Area rain totals after storm

The Bay Area closed out its second multi-day April rain event on Wednesday, with parts of the coastal hills getting more than 3 inches.

Some of the largest amounts fell in parts of Contra Costa County. Crockett, along the Carquinez Strait, was one of the hotspots with 3.44 inches of rain in 48 hours from Monday morning through Wednesday morning. The heavy totals extended into Alameda County and the Berkeley-Oakland hills, with the Lawrence Berkeley National Laboratory recording more than 2 inches.

Downtown San Francisco picked nearly 1.5 inches of rain over the 48 hours, pushing the April total to 2.83 inches. San Francisco International Airport was in a bit of a dry spot for this storm, only registering 0.93 inches. But the airport is still running nearly 2 inches ahead of its April average. 

The Peninsula and North Bay hills also saw high totals. A Pacifica gauge in the coastal hills led the region 3.15 inches, and Mill Valley, Santa Rosa, and Mt. Tamalpais each logged more than 2 inches.

The rain was catalyzed by a moist southwest wind flowing in off the Pacific, funneled through gaps like the Golden Gate and forced upward by the coastal and East Bay terrain. Heavy rain pelted the windward slopes, while lee-side stations east of the Diablo Range barely registered. Pleasanton measured 0.16 inches and Livermore came in at 0.48 inches.

Castro Valley’s surprisingly high total of 2.76 inches was a local quirk from the same pattern. Winds from the southwest funneled through the gap between the Oakland and San Leandro hills and produced a rare lowland maximum in an area that often gets passed over in southwest-flow events.

One observer in the Oakland Hills marked the event with a historical benchmark: two separate one-inch rain days in a single April, the first time that has happened at the site since 2008.

The event caps off what has been a remarkably wet April for a region coming off its driest March on record. Pacifica’s monthly total now stands at 9.70 inches, the highest in the Bay Area. Castro Valley has recorded 7.65 inches, Mt. Tamalpais 7.19 inches, and Crockett 6.61 inches for the month. 

The Sierra added 8 to 12 inches of fresh snow at Palisades Tahoe, Kirkwood and Mammoth. April’s total now stands at 81 inches, pushing the season tally to 359 inches, about 88% of average for the date.