Last time SF saw no rain in February was 1864: 'We're on pace to hit that again'

A sunny day at Dolores Park in San Francisco in February 2020: There's no rain in the forecast through the end of the month. A sunny day at Dolores Park in San Francisco in February 2020: There's no rain in the forecast through the end of the month. Photo: A Graff Photo: A Graff Image 1 of / 5 Caption Close Last time SF saw no rain in February was 1864: 'We're on pace to hit that again' 1 / 5 Back to Gallery

A weak weather system is forecast to deliver light rain to the southern and central parts of California Friday night into Saturday, but meteorologists say it's highly unlikely the San Francisco Bay Area will see a drop.

Earlier in the week there was some hope the South Bay and even the East Bay may see a sprinkle, but National Weather Service forecaster Drew Peterson now puts the rain chances in those areas at 0%.

"The Santa Cruz Mountains have a slight chance of rain, but anything they do get will be very light," said Peterson. "The only thing that seems like more of a sure thing is the higher peaks of Big Sur could see a few-hundredths to a half-inch. The system is aimed at Southern California. San Diego and Los Angeles could see a quarter-inch."

February has been a dry month for the Golden State and none of the NWS weather gauges in the Bay Area — including San Jose, San Francisco, Oakland and Santa Rosa — have recorded any measurable rain. The forecast through the end of the month doesn't include the possibility of any significant storms.

"There has only been one other year where there has been no precipitation in February and that was 1864," said Peterson. "It looks like we’re on pace to hit that again. At this point, we’re all hoping for a March miracle [a wet spring]. We’ve had them before. This is just wish-casting."

The reason for the lack of rain is a weather system known as a high-pressure ridge that's parked in the eastern Pacific Ocean and steering the storm track away from California.

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The National Weather Service measures rain averages using the water year, running Oct. 1 through Sept. 30. In this water year, rainfall totals are falling well below historical averages.

The rain gauge in San Francisco on average measures 17.94 inches between Oct. 1 and Feb. 19, but this year it has received just 8.83 inches, or 54% of normal. The Santa Rosa Airport is at 63% of normal and San Jose 39% of normal.

"We’re in quite the midst of a dry spell and it doesn’t look to be breaking any time soon," said Peterson.

Amy Graff is a digital editor with SFGATE. Email her weather tips and photos at agraff@sfgate.com.