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Record storm dumps 15 percent of SF’s yearly average rainfall on city

Local weather records stretching back to the Gold Rush era broken

Photo by West Coast Scapes/Shutterstock

As promised, the storm that came along with the atmospheric river that blindsided Northern California last week brought record rainfall as well as some troublesome flooding to San Francisco.

In fact, this single storm alone delivered 15 percent of the city’s yearly average rainfall and broke some local weather records stretching all the way back to the Gold Rush era.

The National Weather Service field office in Monterey tells Curbed SF that, in all, 3.43 inches of rain fell on San Francisco from the storm that began Thursday afternoon.

That’s not only more rain than falls on the city during the entirety of an average April, it’s actually more April rain than San Francisco has seen in all but a handful of occasions going back to 1849..

According to Golden Gate Weather Services in 167 years there have only been 18 Aprils in San Francisco that provided more rain than last week’s single storm:

  • 1852: 5.37 inches
  • 1854: 4.99 inches
  • 1879: 10.06 inches
  • 1883: 6.33 inches
  • 1885: 5.28 inches
  • 1895: 5.16 inches
  • 1922: 3.92 inches
  • 1925: 5.26 inches
  • 1934: 3.45 inches
  • 1940: 4.05 inches
  • 1941: 3.65 inches
  • 1957: 5.47 inches
  • 1966: 4.9 inches
  • 1977: 4.21 inches
  • 1982: 3.48 inches
  • 2002: 3.6 inches
  • 2005: 5.02 inches
  • 2009: 3.59 inches

Note that April is not usually a particularly wet month in San Francisco and most years March sees twice as much precipitation.

But this single April storm also delivered more rain than the city got in 114 of the 167 recorded March rainfall totals between 1849 and 2016, and more rain than the city has received in any May on record except for three.

Photo by Tayfun Coskun/Shutterstock

So in terms of springtime San Francisco storms, this was one for the ages. In fact, the National Weather Service reported via Twitter that just this single storm bumped SF’s total rain this year up from 63 percent of the city’s historical average to 78 percent.

The current NWS forecast anticipates a chance of more rain this week, mostly likely on Wednesday evening, but gives it only a 50-50 shot altogether.