A fog-free San Francisco? Scientists ponder California's climate future
A fog-free San Francisco? Scientists ponder California's climate future Nearly 70% of Californians live in coastal counties, which figure to be most impacted by diminished fog.
Show Caption
Hide Caption
Climate change is now impacting where Americans choose to live
Many U.S. locales have reached a climate change "tipping point." Populations are declining as flooding becomes unbearable.
SAN FRANCISCO – As most of the U.S. sweltered in mid-July 2022 − when temperatures in many major cities reached the high 90s and even triple digits − a national weather map showed San Francisco topping out at 65 degrees.
It was just a typical foggy summer day in the city by the bay, which averaged 62 degrees that month, about the same as the next two Julys.
Now the advent of climate change raises the question of whether summertime visitors will stop rushing out to buy sweatshirts upon arrival and instead feel perfectly comfortable in shorts and T-shirts.
The future of San Francisco's iconic fog has been debated in media stories during recent years, and some experts note a diminished cloud cover along the California coast that could lead to a warming trend.
But few if any detect signs that San Francisco's summer chill is going away like the once-celebrated Fog City Diner, which shut down at the end of May.
'From the data, I can't foresee it any time soon,'' said Rachel Clemesha, a project scientist with the Scripps Institution of Oceanography at the University of California-San Diego who studies the state's coastal climate. 'There are years when there's more or less cloud cover. The last couple of years have been within that range. It is a very foggy place, so it would be very dramatic to get you a fog-free city.''
Data on decreasing fog along coast is 'spotty'
Clemesha said some decrease has been confirmed in Southern California in what residents there call the marine layer, mostly in highly urbanized areas, but nothing that applies statewide.
Peter Weiss, a faculty researcher and lecturer at the UC-Santa Cruz department of environmental sciences, said that despite a growing narrative of waning fog along the California coast, the data to support it is 'very spotty,'' with few academic studies in the last decade.
The reasons include the fog's unpredictability – Weiss calls it an 'ephemeral phenomenon'' – and the lack of a standard way to measure it. Some studies, such as the landmark analysis by James Johnstone and Todd Dawson in 2010, rely on airport visibility records. Others use satellite images to determine the extent of the cloud cover, and others yet believe water content is a more valuable gauge.
The airport records are the most extensive, going back to 1950, and Weiss said from that year until 2012 they revealed a 5% decrease in fogginess.
'Nobody's quite sure why,'' he said. 'It probably has to do with the ocean's sea-surface temperature, and that goes through various phases. Overall, there's warming due to global warming, but it's episodic. There appears to be some pattern with less fog after the warmer sea-surface temperatures, but this is still an area of research.''
Many California residents, ecosystems would be affected
While the scientific community endeavors to figure out the long-range impact of climate change on California's coastal fog, there's a strong consensus that diminished cloud cover would have a harmful effect.
Nearly 27 million of California's 39 million residents – close to 70% – live in coastal counties, by far the largest total in the nation, and they generate 80% of the state's gross domestic product. Their lives are certain to be impacted, as would be the state's powerhouse agriculture industry, which totals close to $60 billion a year in revenue.
Species such as the widely admired coastal redwoods, which get up to 40% of their yearly water intake from fog, could be threatened if that resource dwindled.
Daniel Fernandez, an environmental sciences professor at Cal State Monterey Bay, is part of a group seeking a grant from a private foundation to study how climate change may alter fog and affect various ecosystems.
'You could have significant die-off of species that are dependent on the fog at locations where it gets reduced,'' he said. 'It would also change how people live. When you look a fog zones, you don't need air conditioning. There are a lot of things we don't need that we take for granted. Those things could all change.''
It can feel like living in a cloud
The fog, more prevalent in the summer, is created when warm and moist air sweeps over cold waters, which are churned off the California coast by strong winds in what's known as upwelling. The marine cover can be light enough to simply cool down a warm day and thick enough to wet residents' hair and obscure their eyeglasses, giving the impression they're living in a cloud.
Some years the fog is thicker than others, but it tends to be more extensive in Northern California than the state's southern coast because of the differences in their ocean temperature (colder in the north), latitude and topography.
Ian Faloona, a professor of land, air and water resources at UC Davis, said he and a colleague conducted a study using regional climate models and found a downward trend in cloudiness along the coast, but agrees the overall evidence 'is not going to hit you over the head.''
He compares that to the abundant data indicating California in general is warming quickly, about 1 degree Celsius – 1.8 degrees Fahrenheit – per decade. Even San Francisco is heating up a bit, though not nearly as fast: Its average summer temperature has risen by 1.6 degrees Fahrenheit since 1970, according to the independent research group Climate Central.
Two different perspectives on what the future holds
But climate scientists are split over whether the increased heat will lead to less fog because the air over the ocean won't be cold enough to condense, or whether stronger winds will atone for that factor.
'Under climate change, we know the land is warming much faster than the ocean, so that temperature difference across the land and ocean interface is increasing, which could drive stronger winds, which could help preserve this cloudiness,'' Faloona said. 'So there are two arguments you could make about what we theoretically think should happen, and which one's winning out I think is still an open scientific question.''
Sara Baguskas, an assistant professor at San Francisco State University with a specialty in coastal fog, said the lack of conclusive evidence that it's ebbing should not induce complacency but rather stimulate funding to study and predict its patterns.
She's among the climate researchers who have heard from longtime coastal residents saying the marine layer has subsided over the years.
'So it's not unreasonable to be concerned about coastal fog declining in the future, but it diminishing completely is unlikely,'' she said. 'No coastal fog in California is a scary thought for both people and ecosystems.''
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
4 hours ago
East Coast prepares for major heat wave as temperatures reach triple digits
Tens of millions of Americans are under heat alerts as extreme heat hits several parts of the country this week, especially the northeast. Extreme heat warnings issued for Philadelphia, New York City and Boston go into effect on Sunday as the heat ramps up for the second half of the weekend. An extreme heat watch was also issued for Washington, D.C., and Baltimore on Monday. New York City Mayor Eric Adams told reporters Saturday that temperatures will reach the high 90s, and peak heat on Tuesday will be 100 degrees. "The conditions can be deadly and life-threatening if you are not prepared," he said at a news conference. Zachary Iscol, the city's commissioner of Emergency Management Department, told reporters that the city would be activating its emergency heat plan Sunday and opening 248 cooling centers. He advised New Yorkers to limit strenuous activities outdoors and to limit their electricity use, including washing machines, during peak power use. Other parts of the country will also face similar issues due to the high heat. Heat alerts have been issued from Colorado to Maine, including more than 150 million Americans. Heat index values in the Midwest will soar into the triple digits this afternoon, with some areas experiencing feels-like temperatures closer to 105-110 degrees. The extreme heat could be life-threatening. The heat begins expanding east on Sunday with highs soaring into the 90s from the Great Lakes to southern New England. The increasingly humid conditions will make it feel even hotter than that. Heat index values will hit the triple digits across much of the Midwest again tomorrow, including the Chicago area, with parts of the Northeast seeing feels-like temperatures soaring into the upper 90s to near 100 as well. Heat relief will be sweeping into the northern Plains over the next 24 to 48 hours as the extreme heat shifts east in the coming days.
Los Angeles Times
9 hours ago
- Los Angeles Times
Tornado sweeps through North Dakota town, leaving at least 3 dead
ENDERLIN, N.D. — Powerful winds — including a tornado — that swept across parts of the upper Midwest left three people dead and a regional airport heavily damaged, while nearly 150 million Americans were under a heat advisory or warning as the weekend warms up much of the U.S. A complex storm system wreaked havoc in parts of North Dakota, northern Minnesota and northern Wisconsin, with reported tornadic activity, large hail and strong wind gusts, according to Brian Hurley, meteorologist with the National Weather Service's Weather Prediction Center. Cass County Sheriff Jesse Jahner said at a news conference Saturday that two men and a woman were killed at two locations around the town of Enderlin, N.D., late Friday. Enderlin is about 57 miles southwest of Fargo. About 24,000 customers were without power in North Dakota. Hours earlier in a post on the social media site X, the National Weather Service in Grand Forks said two deaths were attributed to a tornado that hit a home. Timothy Lynch, lead forecaster with the National Weather Service office in Grand Forks, said that the storm had been confirmed as a tornado but that crews were still working to determine its strength and highest wind speeds. He said the storm affected the neighboring counties of Cass and Ransom. 'We still have people out investigating and gathering information on what happened. It was a pretty major event,' Lynch told the Associated Press on Saturday. Heavy winds also swept across localized areas of Minnesota. The weather service reported wind gusts of up to 106 mph at Bemidji Regional Airport overnight. 'I cannot ever recall hearing a rushing wind like that!' Bemidji Mayor Jorge Prince posted on Facebook in the early hours Saturday. 'Emerged from our basement to find our neighborhood with lots of trees down and several homes with severe damage.' Prince also said officials were responding to many downed power lines and several gas line leaks. Beltrami County Emergency Management said the damage to the Bemidji area is 'extensive.' Many Bemidji-area businesses posted on social media Saturday saying they were without power and closed for the day. Nearly 34,000 customers in Minnesota were without power, according to Hurley said that same storm is traversing across parts of Michigan but is weakened. It will cross over lower Ontario, Canada, and back into the United States to hit upstate New York on Saturday night into Sunday. 'Still wind and hail threat,' Hurley said of the enhanced risk to upstate New York. 'It doesn't look like it's going to be as robust perhaps as we saw last night.' Almost 59 million Americans were under an extreme heat warning Saturday, Hurley said, as the high temperatures combined with humidity push an above-average heat index for the Northern Plains and the Midwest. Parts of Nebraska, the Dakotas, Minnesota and Iowa could face temperatures 'easily 20 degrees above normal,' Hurley said, including some areas reaching the triple digits. It may be expected in July, he said, but it's rarer to see in June. 'A lot of these areas have been pretty cool with rain over the last month or so, so it's going to be a little bit of a shock,' Hurley said. Cooling centers were open in cities including Omaha and Minneapolis as officials warned the public of dangerously hot conditions. An additional 84 million people were under a heat advisory as forecasters expect the extreme weather to migrate eastward toward the Great Lakes, the mid-Atlantic and the Northeast, where the 'heat risk category is a 4 of 4' into early next week, Hurley said. Meanwhile, parts of the Great Basin and the Southwest may be hot but are seeing relief from below-normal temperatures.
Newsweek
11 hours ago
- Newsweek
Three Killed in North Dakota Tornado Outbreak
Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content. Three people died late Friday in rural Enderlin, North Dakota, after severe storms spawned tornadoes that devastated the area. According to a Saturday statement on Facebook from the Cass County Sheriff's Office, storm chasers discovered two deceased individuals at one location while first responders found a third victim at another site. The tornado outbreak left a trail of destruction in eastern North Dakota and across the Northern Plains, damaging homes, downing power lines, and cutting electricity to tens of thousands of residents. Law enforcement, fire, and emergency crews worked overnight conducting wellbeing checks and search operations, according to the sheriff's office. Why It Matters This deadly severe weather event highlights the increasing frequency and intensity of storms affecting the central United States. The tornadoes and associated winds exceeding 100 miles per hour left thousands without power in North Dakota and Minnesota, disrupting critical services and prompting urgent safety warnings. As the same storm system moved east, forecasters warned of continuing hazards for millions of Americans already coping with a dangerous heatwave, USA Today reported. The disaster serves as a stark reminder of the vulnerability of rural communities to extreme weather and underscores the importance of disaster preparedness, timely public alerts, and coordinated emergency response efforts. Authorities and utility companies face significant challenges in restoring infrastructure and aiding affected populations. What To Know Deputies from the Cass County Sheriff's Office responded to a call about tornado damage at approximately 11:40 p.m. on Friday in rural Enderlin, which is about an hour outside of Fargo and the Minnesota state line. Upon arrival, the Enderlin Fire Department informed deputies that storm chasers had located two deceased individuals, with the third victim found by firefighters at a separate location soon after. Sheriff Jesse Jahner confirmed the victims were two men and one woman, The Bismarck Tribune reported. Their identities have not yet been released. The severe thunderstorms and tornadoes caused significant damage to homes and infrastructure in several parts of eastern North Dakota, including Urbana, Eckelson, and Buchanan. Winds exceeding 100 mph—such as a 101-mph gust near Linton and 111 mph gust recorded in Luverne—were reported by the National Weather Service (NWS) and private weather stations. High winds continue within the red area. THESE ARE LONG DURATION WINDS, lasting over an hour. Gusts have been recorded of up to 100 MPH. Power outages, tree damage, and outbuilding damage are possible. Remain weather aware. #NDwx #MNwx — NWS Grand Forks (@NWSGrandForks) June 21, 2025 The storms also produced large hail, measured over 3.5 inches in diameter, and led to flash flooding, particularly in Fargo and Bemidji, according to local reports. As of Saturday morning, approximately 30,000 North Dakota residents and 57,000 in Minnesota were without power at the peak of outages, according to utility companies and official trackers. Meteorologists attributed the outbreak to a persistent heat dome over the southwestern U.S., which created conditions for destructive thunderstorms across the Northern Plains, Midwest, Northeast, and beyond. Forecasters warned that the ongoing storm system was advancing eastward, with the potential to generate more tornadoes, flash floods, and possibly a derecho event—a long-lived, damaging windstorm—over the next 48 hours, USA Today reported. The extreme weather coincided with a dangerous heatwave affecting more than 150 million Americans, with temperatures reaching 90 degrees or higher across parts of over two dozen states. In this stock photo, a tornado is seen in York, Nebraska, on June 20, 2011. In this stock photo, a tornado is seen in York, Nebraska, on June 20, 2011. Getty What People Are Saying NWS Grand Forks wrote on X, formerly Twitter, on Saturday morning: "High winds continue within the red area. THESE ARE LONG DURATION WINDS, lasting over an hour. Gusts have been recorded of up to 100 MPH. Power outages, tree damage, and outbuilding damage are possible. Remain weather aware." North Dakota Insurance Commissioner Jon Godfread in a statement on Saturday: "While North Dakota is no stranger to summer weather, the scale and intensity of last night's storm were especially significant. Our hearts also go out to those who lost their lives during this terrible storm. If your home, farm, vehicle, or business sustained damage, the most important thing you can do right now is to act quickly, document everything, and protect your property from further harm." What Happens Next? Disaster recovery information for North Dakota residents is available at and by contacting the Insurance Department at 701-328-2440. Authorities plan to continue welfare checks and damage assessments throughout the affected region, while utility teams work to restore power. The NWS and emergency agencies have urged residents to monitor forecasts as the storm system proceeds eastward, with hazardous weather expected in additional states over the next several days.
