Is The City in danger of losing its chilly climate identity?

San Francisco has long championed itself as a temperate paradise — even if it didn’t feel that way to start the month.

The City opened July with its hottest stretch of the year, with San Francisco falling under a National Weather Service-issued heat advisory through the Fourth of July.

But San Franciscans know that these summer warm-ups — despite increasing in frequency — remain the exception, not the rule.

The City’s year-round climate has generally kept its cool and breezy identity, even as the rest of the nation has boiled under record-breaking heat waves through much of the first half of the year.

And, as The Wall Street Journal reported last month, The City’s tourism bureau has noticed . San Francisco travel officials told the outlet that they intentionally began promoting The City’s chill as an escape from the nationwide heat last year and plan to continue doing so this summer.

But with global warming threatening so many previously hardened climate realities, it raises a question: Will San Francisco always be able to insulate itself from the simmering nationwide summer heat?

The short answer, according to weather experts who spoke to The Examiner, is yes — because San Francisco lies along the Pacific Ocean.

If anything, climate researchers said, rising global temperatures will only bolster The City’s role as a weather refuge.

“San Francisco might become more of an escape, honestly, because inland temperatures are expected to rise much faster than oceanic temperature,” said Paul Ullrich, head of climate resilience at Lawrence Livermore National Lab.

“It will continue to be a respite, if not a growing respite from change,” he said.

The Pacific Ocean — the temperature of which generally stays between the high 40s to low 50s, with its water flowing from the Gulf of Alaska — has long served as a built-in cooling device for The City. The marine layer — the thin blanket of moist air along the ocean that creates low-lying clouds and fog and traps cool air in cities near the coast — insulates San Francisco from flaring up.

Sometimes, though, like during this week’s heat wave, even the marine layer isn’t strong enough to protect The City from baking.

Jan Null, a San Francisco meteorologist for the last 50 years, said that phenomenon occurs when a high-pressure system builds over the entire city, not just from inland, and consequently suppresses the marine layer.

Ullrich said these events are due to atmospheric conditions not associated with climate change.

“When you get these high pressure ridges or when you don’t is kind of all random chance,” he said.

The future of San Francisco’s fog — a product of the marine layer — has become a point of uncertainty in recent years . Fog science, overall, remains imprecise and a challenge for scientists to get a grip of, the experts said.

Null vehemently pushed back on the idea that The City is in danger of losing one of its defining characteristics.

“It’s not going to disappear as long as we have the Pacific Ocean where it is,” he said.

Ullrich said he was more open-minded than Null. He said there are data that suggest there’s been a significant decrease in the amount of fog since before the 1970s. But, he said, it’s unclear how much of that is driven by climate change or due to “natural variations in the climate system.”

“I’m confident that there is a decrease in the amount of fog that we’re getting,” he said. “But it’s very difficult to put a number on when we’re going to see significant decreases in that without knowing how much of that is connected to natural variability and how much is connected to what we do to the climate system.”

Of course, The City’s weather has been far from immune to climate change stemming from the incessant burning of fossil fuels.

The average temperature in downtown San Francisco has increased from 64 degrees from 1961 to 1990 to around 66 degrees in the present day.

From 1960 to 1990, San Francisco experienced an average of three to four extreme heat events — defined as any day in which the mercury reaches 85 degrees Fahrenheit or higher. That number has climbed to an average of five at present and is projected to rise to seven between 2030 and 2060.

San Francisco is also less equipped to deal with those ramifications than many other cities.

The City has the lowest rate of air-conditioner ownership in the nation. Outdated buildings, concrete and a lack of trees have created multiple urban heat islands — areas that are particularly susceptible to warming during extreme heat events — across San Francisco.

A year ago, The City announced a plan to bolster its infrastructure so it can be more resilient to the increasingly warm temperatures coming to San Francisco.

In addition, Ullrich said that while the timing of the current heat wave is “fairly normal,” the length and severity of it are notable.

“The occurrence of this particular heat wave was not anomalous,” he said. “There is certainly a fingerprint of human activity on it, which was responsible likely for driving up temperatures by maybe 2 degrees Fahrenheit more than what we might have experienced before industrialization.”

But climate scientists maintain that even as The City gets hotter, its overall climate will always be moderate relative to other states or even inland Bay Area cities. That means it will always serve as a pseudo-cooling center for many Americans.

“Let’s say that average high temperatures around California over the next 20 years go up 4 degrees — an extreme number,” Null said. “Well, that also means that Sacramento will go up 4 degrees. And even if San Francisco goes up four degrees, the difference between the two is still a lot cooler than the other places.”

Null, like Ullrich, also noted that research suggests climate change will heat up inland cities far more than those near the ocean.

“San Francisco, being a peninsula surrounded by water, it’s going to stay relatively temperate,” he said. “It may be elevated at a couple different points, but it’s still gonna be so much cooler than any other place relative to all these other places. If we’re talking about tourism, it’s still going to be 40 degrees cooler than it is in Atlanta.”