Is the Heat Dome a Freak Occurrence, or “the Coldest Summer of the Rest of Our Lives”?

On Monday afternoon, Portland experienced its hottest day in history—for the third consecutive day.

A 116-degree temperature recorded at Portland International Airport on June 28 exceeded the 112 degrees experienced on Sunday, June 27. That number, in turn, shattered the all-time record set on Saturday, June 26: 108 degrees.

On social media, people are experiencing a meltdown. Many people trying to endure the oppressive heat dome that’s descended on Portland are voicing the fear that, as the planet warms, this misery is as good as it gets. “The coldest summer of the rest of our lives”—that’s the new meme.

Dr. Paul Loikith says that’s an understandable reaction, but not one grounded in climate science.

Loikith is director of the Climate Science Lab, an associate professor in the geology department at Portland State University, and an expert on extreme weather. He sat down with WW (virtually, of course) on Monday morning to help explain what factors contributed to creating the three hottest consecutive days in Portland in its recorded history.

The adjective he uses to describe the heat dome? Diabolical.

“It’s almost diabolic, the makeup of this system. If meteorologists sat around and talked about how can we make the most extreme heat event in Portland, these are all the ingredients we would put in,” Loikith says. “And we would probably think, what are the chances of all those coming together? It’s extremely unlikely.”

So first: Here’s the meat and potatoes of the heat dome.

“We have a really remarkably unusual weather pattern that’s driving this heat,” Loikith explains. “The overall driver is a broad area of high pressure in the atmosphere, so what’s happening is warm air from lower latitudes has surged northward over the Pacific Northwest—we refer to that meteorologically as an atmospheric ridge of high pressure. And then other interesting things happen underneath a ridge, and they’re just happening to a really extreme degree over the Pacific Northwest. So already you have really hot air getting displaced northward, and then air tends to sink under an atmospheric ridge, and as it sinks it compresses and warms. So that adds extra heat to this hot air mass.”

Surges of wind from the interior, too, have prevented any cooling effects from the Pacific Ocean that normally help Portland stay cool in the summer. Then, to our east, air has been descending down the Cascades toward Portland, and when that air sinks, its temperature rises.

“So we don’t have the cooling influence of the ocean, we have an extremely hot air mass, and we have local wind patterns that are adding additional heat on top of that, which are conspiring to make this a truly remarkable and almost unbelievable heat event across the region,” Loikith says.

In layman’s terms? It’s a very unfortunate confluence of weather factors that, after all is said and done, are a huge bummer for Oregon.

So it’s just a freak occurrence, not climate change? Nah—it is a factor. Even without a warming planet, the heat dome could still happen. It just wouldn’t be as hot.

“We know that climate change is making everything warmer, so our cool events aren’t as cool as they used to be and our hot events are hotter than they use to be. So at the simplest level, we can say with a lot of confidence that an event like this would be less likely to be this hot decades ago,” Loikith says.

He adds that “it would’ve been an extremely hot event anyway, but with added background warming, the magnitude of the heat is likely to be higher.”

Climate scientists have explained the increasing likelihood of extreme events like the heat dome by using the analogy of “loaded dice”—the odds of a horrible outcome increase each summer. Loikith says that’s not the same thing as expecting each year to include these kinds of temperatures.

“We need to be careful to resist the temptation to make too many climate scale conclusion based on one weather event,” he says. “Just because you have one extreme event, it doesn’t tell you a whole lot about what weather events going forward are going to be like.”