S.F. has full season’s worth of rain already

As of Saturday, seven months into the 2022-23 rain season, San Francisco had received a full season’s worth of rainfall, according to meteorologists.

A quarter of an inch that fell in the morning and early afternoon Saturday put San Francisco over the top by 2 p.m.: It brought the total precipitation during the current rainfall season — July 1 to June 30 — up to 22.89 inches, according to meteorologist Jan Null of Golden Gate Weather Services.

“This equals their full season (July-June) normal,” he tweeted.

For comparison, downtown San Francisco normally gets 12.87 inches of precipitation from July 1 to Jan. 30, Null tweeted.

“And there are several more months in the rainy season,” he added.

The weekend weather system that brought the key rainfall milestone continued to bring “beneficial rain” to the Bay Area on Sunday, as well as widely scattered, pea-size hail and isolated thunderstorms, the National Weather Service reported.

Nearly an inch of rain fell on some parts of the Bay Area, before showers tapered off late Sunday afternoon and early evening, giving way to pockets to sunshine as a cold upper level trough moved southeastward, the Weather Service said. Lows Sunday night were expected to drop into the 30s and lower 40s.

Meanwhile, the Sierra near Lake Tahoe ski resorts saw 5 to 10 inches of snow over the weekend, the weather service said. Whiteout conditions Sunday led to major traffic headaches for those traveling on I-80. Spinouts over Donner Summit caused closures in both directions on I-80, as well as eastbound State Route 20, according to Caltrans.

More Bay Area rain was expected Sunday night before the skies clear for the workweek.

And still more rain is on the way at week’s end, according to Chronicle newsroom meteorologist Michelle Apon. “This upcoming weekend and into next week (Super Bowl weekend into Valentine’s Day) looks promising for precipitation across the Bay Area,” she said. Yet another storm may bring rain to the region the third weekend of February, she added.

“Weather models can be uncertain the farther we go out from today, but it’s fun to keep an eye on it and hope these storms come to fruition,” she said.

Despite the “impressive parade” of atmospheric-river storms that dumped record amounts of precipitation as they swept over the Bay Area in December and the first half of January, Null noted, the JulyJanuary rain total didn’t quite crack the historical top 10 for San Francisco. According to the National Weather Service, San Francisco’s rainfall total so far makes it the city’s 11th wettest season to date.

The wettest July-January period ever recorded in San Francisco occurred in 1861-62, with a total of 38 inches, Null said. The most recent period exceeding the current total was 1997-98, when 23.6 inches fell.

The rainfall year is measured from July 1 to June 30, according to the weather service. A separate precipitation measure called the water year runs from Oct. 1 through Sept. 30.

“This upcoming weekend and into next week (Super Bowl weekend into Valentine’s Day) looks promising for precipitation across the Bay Area.”

Michelle Apon, newsroom meteorologist