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Cold snap coming to San Francisco, overnight temps could hit lowest point in 6 years

Overnight temperatures in certain San Francisco neighborhoods could dip to near-freezing temperatures, according to ABC 7 Meteorologist Drew Tuma. As such, San Franciscans will want to take certain precautions with their pets, plants and property.

“Bring your pets inside,” Tuma said in an interview with The Standard. In the coming days, the city’s official National Weather Service outpost in the Lower Haight might just record a low of 38 or 39 degrees Fahrenheit—which would be the chilliest reading in the past 6 years.

Also, anyone with particularly sensitive plants on the porch, balcony, or window sill should consider bringing those indoors, as well. David Stoner, president of Sloat Garden Center, said he is expecting San Francisco to experience frost over the next night or two. While frost is unlikely to deal a death-blow to established plants, it can damage the folliage.

The best course of action for proactive plant parents, according to Stoner, is to bring your plants inside. You can also move them under an overhang, or cover them with a frost blanket.

Stoner also noted that most plants prefer to be well watered when entering a period of extreme cold. The one exception to that rule: succulents and cacti. These, he said, should be as dry as possible heading into cold weather.

The reason the leaves of your burros tail, candelabra aloe, zebra plant and jade tree are so fleshy is that they are filled with water. And when those leaves approach freezing, the ensuing frost can damage the tender cells of those leaves, leaving the same plant that survived weeks without water in direct sunlight with withered, frost-bitten leaves.

Succulents are hearty, but they can be damaged by frost. | Getty Images

As for concerns over bursting pipes, Tuma said it’s always possible that temperatures approaching freezing could deal a final blow to older plumbing, though this issue is more common with sub-freezing temperatures.

San Francisco hasn’t officially recorded a temperature of 32 degrees Fahrenheit since 1990—even as it’s relatively common for areas directly north, south and east of the city to dip below freezing a few times every winter.

That’s due to something called the “urban heat island” effect, Tuma said. Winter temperatures never get far below freezing anywhere in the Bay Area; as such, the remaining heat that San Francisco’s concrete, asphalt, metal and glass surfaces continue to radiate after sunset helps keep the city warmer than its suburban and rural neighbors.

Tuma had two more notes for locals bracing for the cold snap.

First, the good news: It’s possible that the dip in temperatures could pull some of the pollen out of the air, which might bring relief to allergy sufferers.

Second, he said, don’t be too hard on yourself if you feel cold. The first couple of cold days after a warm spell like we just had can be jarring to the body.

“Wear your gloves, wear your hat,” Tuma said. “I know we get the reputation for being weak, but your body’s not used to it.”

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