What causes fog in San Francisco in the summer?
What Causes Fog. Fog covers San Francisco the most in the summer when the cold wind off the Pacific Ocean hits the heat of inland California. As the hot inland air rises, the cool ocean breeze off the Pacific replaces it, creating the fog effect.
Does San Francisco's Fog have a name?
^ Kathryn Prociv, "Capital Weather Gang: Pic of the week: San Francisco's fog has a name. It's Karl", The Washington Post, May 20, 2016.
What to do in San Francisco when it’s Foggy?
In the morning, wander through some of the most iconic destinations in the city while they are shrouded in fog. You can walk across the Golden Gate Bridge or the Golden Gate Promenade, or visit Crissy Field, the Marina Green, and Fisherman’s Wharf.
Why is San Francisco so cold and dry?
But San Francisco got left out of the hot, dry part, due to its position on the tip of a peninsula surrounded by very cold water. San Francisco also benefits from the contrast between the cold ocean current and the extreme heat of California's Central Valley.
Why is San Francisco so foggy?
San Francisco's fog is a meteorological phenomenon. Hot air rises away from the city, and the rising air mass creates a low-pressure zone. This zone sucks in cold, moist air from the Pacific Ocean, which brings moisture into the local climate. As the air cools below the dew point, Karl condenses.
Is San Francisco the foggiest city?
San Francisco, California. While San Francisco may not be at the top of the list in terms of number of foggy days, fog is famous in San Francisco. In fact, even though the City By The Bay only sees half of the foggy days as Cape Disappointment, no place on Earth is more associated with fog.
Why is Bay Area foggy?
How Does It Happen? Although fog can occur sporadically year-round, it mainly blankets the coastal Bay Area in the summer when hot inland temperatures create a low-pressure zone over Northern California's Central Valley. The hot inland air rises and the heavier cold ocean air rushes in to replace it.
Is there a lot of fog in San Francisco?
As the city of San Francisco lies adjacent to the Golden Gate, it is often subject to the fog and low clouds blowing in on the marine layer. Even when the clouds are not present, the coolness of the marine layer exacerbated by the strong winds can chill the city even in mid-summer.
What's the foggiest city in the world?
Share this:We'll take Hamilton, New Zealand — the country's fourth most populated city — covered in fog or sunshine. ... Karl Mondon/Bay Area News Group. ... Newfoundland, especially the underwater plateaus known as The Great Banks, is the foggiest place on Earth, according to World Atlas. (More items...•
How long does San Francisco fog last?
Fog can be seen in San Francisco Bay pretty dependably starting in June and lasting through August. The fog usually rolls in during the early morning, then burns off by the afternoon, revealing sunny, clear skies, until it returns again in the evening.
Is SF getting less foggy?
However, as our climate has changed during the past few decades there has been a noticeable drop in the amount of Summer fog moving through San Francisco. The data below shows over the past 100 years we've seen a -34.5% decrease in fog which equates to about 3 to 4 hour less fog per day.
Where is it foggiest in San Francisco?
The foggiest San Francisco neighborhoods include Ingleside, Mount Davidson Manor, Oceanview and Stonestown, which all receive an average of 12 hours of fog each day.
What is San Francisco fog called?
Karl the Fog“Karl the Fog?” Yes, you read that right. The shallow fog that often engulfs San Francisco and the iconic Golden Gate Bridge goes simply as Karl, and has a Twitter account, @KarlTheFog.
Why is Golden Gate Bridge so foggy?
The Golden Gate Bridge has an influence in directing fog as it pushes up and pours down around the Bridge. "Advection fog" forms when humid air from the Pacific Ocean swoops over the chilly California current flowing parallel to the coast.
Why is California so foggy?
The lush kelp forests along the California coast exist because of upwelling. And the water from the deep ocean is really cold, which makes fog form over the areas of upwelling. The fog rolls in from the ocean onto land in the morning as the rising sun heats up the land.
Why does San Francisco have so many homeless?
Strong economic growth has created hundreds of thousands of new jobs, but coupled with severe restrictions on building new housing units, it has resulted in an extreme housing shortage which has driven rents to extremely high levels.
Where is the foggiest place in the world?
NewfoundlandThe title of foggiest place in the world goes to an area of the Atlantic Ocean called Grand Banks, lying off the coast of Newfoundland. The area forms the meeting place of the cold Labrador Current from the north and the much warmer Gulf Stream from the south.
Is Pacifica always foggy?
One common misconception is that Pacifica is always cold and foggy. If you're close to the ocean then yes, you're likely to experience a lot of this weather but that's not the case for every neighborhood. Because it's a hilly area, the fog gets trapped on the ocean side, leaving much of eastern Pacifica warm and sunny.
What is the coldest neighborhood in San Francisco?
Telegraph Hill, the oldest neighborhood in SF, is also the warmest. the coldest neighborhoods in San Francisco. Nob Hill is the windiest.
Is Daly City foggy?
By definition, very simply, fog is a low lying cloud that produces water droplets and reduces visibility. There is A LOT of that going on in Daly City. The picture above was taken during this summer at the intersection of Gellert and Hickey right off the Hickey exit in Daly City.
Why is fog decreasing in California?
The decline in fog is generally attributed to climate change, and is concerning for the local ecology, for example the redwood trees.
Where does fog enter San Francisco Bay?
Land-sea temperature gradient. Fog enters San Francisco Bay through the Golden Gate, seen here in August 2012. The prevailing wind along the California coast is from the northwest owing to the normal location of the North Pacific High, a large area of high atmospheric pressure. As the coastline is oriented from northwest to southeast, ...
Why is fog overcast?
These extended periods of cloudiness are usually a consequence of a weak area of low pressure above the marine layer which increases its depth , making it more difficult for surface heating to evaporate the clouds within it. These periods of persistent overcast have inspired colloquialisms such as "June Gloom", "No Sky July" and "Fogust".
What is fog over the Golden Gate Bridge?
Fog over the Golden Gate Bridge (May 2009) Fog is a common weather phenomenon in the San Francisco Bay Area as well as along the entire coastline of California extending south to the northwest coast of the Baja California Peninsula. The frequency of fog and low-lying stratus clouds is due to a combination of factors particular to the region ...
What happens in the late afternoon?
By late afternoon, the wind increases and begins to cool the onshore marine layer, allowing the fog and low clouds offshore to progress inland without evaporating.
How does the Pacific Ocean contribute to fog?
The Pacific Ocean contributes to the frequency of fog by providing atmospheric moisture and by its temperature. It is also the major source of nuclei for the condensation of moisture from vapor into cloud droplets. Moisture evaporated from the ocean surface over hundreds, even thousands of miles of the open Pacific is carried to California ...
What happens when the marine layer encounters the colder waters along the California coast?
When the marine layer encounters the colder waters along the California coast, it cools to its dewpoint, and if small particles called condensation nuclei are present, liquid water drops will form. Condensation nuclei in coastal fog are mostly composed of salt from surf and spray, with lesser amounts of iodine from kelp. These nuclei are so effective that condensation can occur even before the dewpoint is reached.
Why is fog in San Francisco?
Fog covers San Francisco the most in the summer when the cold wind off the Pacific Ocean hits the heat of inland California. As the hot inland air rises, the cool ocean breeze off the Pacific replaces it , creating the fog effect. This flow of air to the low-pressure zone over Northern California's Central Valley pulls the fog through the Golden Gate passage and into San Francisco Bay.
What city is famous for fog?
The fog is so famous, in fact, that locals even gave it a name—Karl—and a cheeky fan page on Twitter. While it's not exactly the sunny California weather visitors may expect, the cool fog does lend the city of San Francisco a mysterious and romantic atmosphere.
Where to see fog?
If that's not you, you can get a pretty splendid view of the fog along Crissy Field, the Golden Gate Promenade, Marina Green, and Fisherman's Wharf, where there's significantly less wind ...
Where does fog creep?
The fog creeps in between the arches of the Golden Gate Bridge towers, then flows over the Marin Headlands, until it hits the shoreline piers. Very rarely is the whole city enveloped by fog; most often, some areas of San Francisco are still visible. George Rose / Getty Images.
When does fog roll in?
The fog usually rolls in during the early morning, then burns off by the afternoon, revealing sunny, clear skies, until it returns again in the evening. So make sure to set your alarm in the morning or prepare to stay up later to see it. The fog creeps in between the arches of the Golden Gate Bridge towers, then flows over the Marin Headlands, ...
When is the best time to visit San Francisco?
For those who prefer sunshine, it's best to book your San Francisco trip between September and November, when the days are actually warmer than in the summer. During the fall, temperatures are comfortable and hover in the mid-70s, with clear, cloudless skies. This is also prime time for beachgoers.
Who wrote the poem "The fog comes on little cat feet"?
As Carl Sandberg wrote in his well-known poem "Fog," "The fog comes on little cat feet. It sits looking over harbor and city on silent haunches and then moves on.". Sandburg wrote these evocative and memorable words not about San Francisco, but rather about Chicago.
Why is the Bay Area fogging up in summer?
There is a system of high pressure over the Pacific Ocean called the North Pacific High. In the summer, it gets stronger, creating big clockwise winds over the ocean.
How much has fog decreased in the Bay Area?
The amount of summer fog has decreased 33 percent over the last century, studies have found. Warming oceans and climate change could continue to affect the complicated weather systems that create our unique Bay Area fog and wind.
Why does fog come in the summer?
The fog comes inland in the summer for similar reasons as the wind: While it stays cool by the ocean, the high temperatures inland create lower pressure, and the fog is sucked in through gaps in the mountains, like the Golden Gate.
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Why is it windier in the afternoon?
Why it's windier in the afternoon. Air always moves from areas of high pressure to areas of low pressure. Hot air rises and is less dense, and is typically low pressure, while cold air sinks and is dense, and is typically higher pressure. Over the course of the day, the air inland heats up in California. But air remains cool over the ocean — ...
Why does San Francisco have fog?
So San Francisco can have any of these types of fog due to the abundance of water. And, the water is cool (because of the currents from the north) which could cool the land off quicker at night. Sea fog is a concern when a cold airmass moves in from the ocean. The cold moist air would cause dense fog.
Why does fog form in colder air?
Colder air holds less moisture. So it becomes saturated more easily. Fog can easily form in colder moist air
What is the fog in Big Fish?
In the case of the fog, Karl is a reference to the giant in the 2003 Tim Burton flick Big Fish, writes the account-holder. "Karl was the giant in town everyone was afraid of because they thought he would kill/eat them. Turns out he was just hungry and lonely." In San Francisco, that giant is the fog. "Karl is a constant character in our lives. ... Some people love how he keeps the city cool, others hate that we don't get traditional summers. They spot him from all over S.F. and many people have choice words for his arrival. Everyone knows and sees the fog.
What is the color of smog?
Pale orange is a typical color for smog; that is, a mixture of smoke and fog, that has sunlight shining through it. When air pollution was more rampant, this was an everyday occurrence in the Spay…, I mean, Bay Area and Hellay… I mean greater L.A..
Why is the water cold?
The water is so cold because of the predominant northwesterly winds. This circulation pattern caused upwelling or cold water from deeper below to rise to the surface.
Is Central Valley hot or cold?
As the interior cools late afternoon, the yet cooler air from the ocean is sucked in, and that air is foggy during those months. This makes SF cool (COLD) during summer, just as Mark Twain noted, but the poor CV doesn’t feel much relief as the foggy air doesn’t penetrate into the Valley too far ..
Does humidity make fog?
This is an option but typically we don't see a huge increase in moisture over short periods of time. But if the moisture content is high enough as it is, then additional moisture would help make fog .
When is fog season in San Francisco?
Note: Fog season is May, June and July, and often August, but mainly out in the western part of SF.
When does fog come out of the bay?
The fog typically shows up offshore around 2:30 to 3:00 pm. Then it rolls in through the Golden Gate, across the bay and sometimes up into the Berkeley Hills.
What is the best outer layer for fog?
A jacket or sweatshirt with a hood is the best outer layer; the wind can be cold and strong when the fog starts to come in. But an hour later, the fog may burn off and it's getting warm, so a t-shirt or light long-sleeved shirt would be more comfortable. Or the other way around.
What is the climate in San Francisco?
The good news: San Francisco has a very mild climate. It rarely gets out of the 55 to 65 degree range (12 to 18°C), summer or winter.
When is the best time to visit San Francisco?
Our warm and sunny months are September and October. The air is clear and golden and the city looks its best. It can even get hot (in the 90's, 32 °C+! ), but that only lasts 2 or 3 days before our natural air conditioning kicks in: offshore fog...yay. During our "heat waves", the fog stays way offshore and there's not a cloud in the sky.
Is San Francisco foggier than the rest of the city?
As a result, the outer neighborhoods near the ocean (the Sunset and Richmond districts) tend to be a lot foggier than the rest of the city. The weather forecast for San Francisco comes in two parts: the coastal area and the rest. Bay Area Summer Weather.
Is San Francisco hot or cold?
The bay counties surrounding SF get very warm in summer, often really hot, and see sunny skies every day, while San Francisco sits in its cool, foggy spot all summer. But even within San Francisco there are noticeable differences in temperature and sun.
Overview
Fog is a common weather phenomenon in the San Francisco Bay Area as well as along the entire coastline of California extending south to the northwest coast of the Baja California Peninsula. The frequency of fog and low-lying stratus clouds is due to a combination of factors particular to the region that are especially prevalent in the summer. Another type of fog, tule fog, can occur during the win…
Ocean moisture
The Pacific Ocean contributes to the frequency of fog by providing atmospheric moisture and by its temperature. It is also the major source of nuclei for the condensation of moisture from vapor into cloud droplets. Moisture evaporated from the ocean surface over hundreds, even thousands of miles of the open Pacific is carried to California from various directions. This water vapor contri…
Land-sea temperature gradient
The prevailing wind along the California coast is from the northwest owing to the normal location of the North Pacific High, a large area of high atmospheric pressure. As the coastline is oriented from northwest to southeast, the marine layer and any clouds present within it would be confined to the coast and adjacent offshore waters, and often are, but for the large difference in tempera…
Variations
A land-sea temperature-pressure gradient is not always necessary to drive the marine layer and low clouds onshore into the Bay Area. Winds ahead of an approaching cold front or low pressure system can also push the marine layer onshore.
Another pattern variation occurs in connection with heat spells that reach the coast from inland. Such heat waves typically occur when an area of high atmospheric pressure orients itself in suc…
Climate change
Research published in 2010 showed that summertime fog in California decreased by 33% during the 20th century. The decline in fog is generally attributed to climate change, and is concerning for the local ecology, for example the redwood trees. The attribution of the reduction in fog and of global warming itself to the Pacific decadal oscillation is generally rejected.
Art and culture
Writers, poets, and photographers have long been inspired by the fog, including Herb Caen, Jack Kerouac, August Kleinzahler, and Arthur Ollman. Sam Green made a film about San Francisco's fog for the Exploratorium, which premiered in 2013. In Kyle Boelte's 2015 book The Beautiful Unseen: Variations on Fog and Forgetting, San Francisco's fog becomes a metaphor for grief and the limitations of memory.
In popular culture
In 2010 an anonymous person began a Twitter account for the San Francisco fog, inspired by the fake BP public relations account that appeared after the oil spill in the Gulf of Mexico that year, and named "Karl the Fog" after the misunderstood giant in the 2003 film Big Fish. The name has since come to be widely used, There is a companion Instagram account. The name is also used throughout episode 8 of Carmen Sandiego. The name was disparaged by 3 local celebrities durin…
External links
• Fog Today: Live satellite view of San Francisco coast and bay
• Media related to Fog in San Francisco at Wikimedia Commons
• Karl the Fog on Twitter