Introduction to San Francisco’s Unusual Summer
Time to cue that famed quote, often falsely attributed to Mark Twain: “The coldest winter I ever spent was a summer in San Francisco.” It’s a cliche, sure. But this year it rings true. It really has been quite chilly in the City by the Bay, which is experiencing its coldest summer in decades, with no significant warm-up in sight and daytime highs topping out in the mid-60s.
Temperature Anomalies in the Bay Area
In downtown San Francisco, the average temperature in July has been 59.3 degrees, about one degree below normal, Matt Mehle, a meteorologist at the National Weather Service in Monterey, said Saturday. The average temperature in San Jose in July has been 67.4 degrees, about two degrees below normal, he said. And in Oakland, as of Saturday, the temperature had reached 75 degrees or higher just one time in July, compared with three times in February.
Historical Context of the Cold Summer
“It’s not record-breaking — but at this point, we’re looking anywhere from 20 to 30 years since we’ve had this cold of a summer,” said Mehle, noting that the area last saw similar weather patterns in the late 1990s. Mehle said a seasonal high-pressure system that typically brings warmer weather is somewhat misplaced this year, sitting farther west than normal. This summer, he said, a low-pressure system has been parked over the Pacific Northwest and California, leading to unrelenting cloud cover and cooler temperatures.
Causes of the Unseasonable Weather
The “misplacement” of the high-pressure system, he added, has contributed to increased upwelling, a process by which strong winds bring deep, cold ocean water closer to the surface. When the wind blows over this colder water toward land, it brings the temperatures down. “The coastal upwelling has been really notable right outside the San Francisco Bay and west of Point Reyes,” Mehle said.
Impact on Daily Life and Future Weather Expectations
In the coming days, the drizzly gray weather along the coast is not expected to change much, said Mehle, who drove to work in Monterey on Saturday with his windshield wipers swishing. “We’re basically locked in,” he said of the weather conditions. Even in San Francisco, where countless summer tourists have unexpectedly shelled out money for sweatshirts and scarves, the chill has been the talk of the town. Nudist Pete Sferra, who keeps a journal describing how many times he walks the city in the buff, told The San Francisco Standard this week that he has “actually been enjoying quite a few nude strolls this year.” But even he would not go out “if it’s freezing.” Walnut Creek resident Lisa Shedd, 60, told The Mercury News: “I certainly love the temperate weather. I’m not a fan of the really hot. I don’t know if it means something bad or it means something good … but I know I’m enjoying it.”
Contrasting Weather Patterns Across California
Farther north, this summer has brought oppressive inland heat and dangerous lightning storms. In Orleans — a tiny northeastern Humboldt County town near the site of the massive, barely-contained Butler fire in the Six Rivers and Klamath national forests— temperatures had been above 100 degrees seven times this month as of Saturday, according to the National Weather Service. In Redding, the temperature had hit 100 degrees or higher 11 times this month, topping out at 109 on July 11. Mild summer temperatures in Los Angeles, where the downtown high has averaged about 82 degrees in July, also have been satirized.
Conclusion
While the cold summer in San Francisco might be a welcome change for some, it’s a reminder of the unpredictable nature of weather patterns. As Mehle warned, “while we started off colder, that doesn’t mean that summer is over.” The hottest temperature ever recorded in downtown San Francisco, he noted, was 106, on Sept. 1, 2017. “We’re sitting here under drizzle, clouds, in the cold,” Mehle said. “It’s the end of July. But summer is not over when you look at our climatology. Some people want slightly warmer temperatures — but you have to be careful what you wish for.”
FAQs
- Q: Is this the coldest summer San Francisco has ever experienced?
A: According to Matt Mehle, it’s not record-breaking but is the coldest in 20 to 30 years. - Q: What is causing the cold summer in San Francisco?
A: A misplaced high-pressure system and a low-pressure system over the Pacific Northwest and California are contributing to the cooler temperatures. - Q: Will the weather warm up soon?
A: As of the latest forecast, the drizzly gray weather is expected to continue with no significant warm-up in sight. - Q: How does the weather in San Francisco compare to other parts of California?
A: Other parts of California, like the inland areas, are experiencing much hotter temperatures, with some areas reaching over 100 degrees multiple times in July. - Q: What is the historical context of San Francisco’s weather patterns?
A: Similar cold summer patterns were last seen in the late 1990s, indicating a cyclical nature to the city’s weather.
