Is a cool summer a cruel summer? If so, Taylor Swift might need to jet back to Seattle soon. Because my outlook for the next couple of months suggests a higher-than-usual shot at cooler temperatures across Western Washington.

But before local Swifties and warm-weather enthusiasts (I see you, California transplants) go berserk, let me add this important caveat: I think the summer months are likely to run cooler than normal by modern-day standards. As in, since Taylor Swift started putting out records—not since 1945, when record-keeping for the city began at Sea-Tac Airport. As it turns out, using the past decade to determine what “normal” Seattle summer temperatures are makes quite a difference. Let’s dig in and see why.

Today’s cool summers: your father’s hot summers

It’s no secret that Seattle’s summers have warmed significantly over the last 10 years—a fact often shared all-too-eagerly by dyed-in-the-wool locals who long for the days when hitting 90 degrees was an aberration, not an expectation. But just how much summers have warmed in such a short timespan is rather shocking. Consider this not-so-cool stat: In 1973, the average Seattle summertime temperature (calculated over the preceding 10 years) was 63.7 degrees. In 2013, that number had risen to 65.3. And in 2023? It stood at 67.5 degrees.

In other words, Seattle summers have warmed more in the past 10 years (2.2 degrees) than in the preceding 40 years (1.6 degrees). The net result of all this drastic warmth is that the “hot” summers of yesteryear are cool summers by today’s standards. And that’s where the summer of 2024 enters the conversation.

The death of El Niño, the rise of La Niña, and what it all might mean for 2024

From mid-2023 until recently, the Seattle weather scene was mostly ruled by El Niño—the global weather phenomenon in the equatorial Pacific Ocean that typically brings milder fall and winter weather to the Pacific Northwest. But El Niño is collapsing as we speak, with scientists estimating it’ll be toast by July. In its place, there’s a good chance that a La Niña will start to take shape, with NOAA predicting a nearly 70 percent chance of La Niña conditions settling in between July and September. La Niña typically has the opposite effect of El Niño on fall and winter weather in Western Washington, with temperatures usually running on the cool side and substantial snow piling up in the mountains.

The long and short of all this is that the summer of 2024 will likely be marked by a shift from El Niño conditions to La Niña conditions—and if recent history is any guide, this means the deck is stacked toward below-average temperatures in Seattle. For proof, let’s look at a few recent examples of Seattle summers where El Niño gave way to La Niña.

The most recent—and probably the most relevant—example is the summer of 2016, where Seattle had just come out of a strong El Niño, not too unlike the one that dominated the winter of 23–24. While the summer of 2016 was not without its stretch of hot days—Seattle hit 90 degrees six times that August—July actually ran slightly cooler than normal, with the city not even touching 80 until the 20th. The first half of September was likewise cool, with the mercury frequently failing to reach 70.

Now, here's where it gets really interesting. The average temperature for the summer of 2016 (June 21–September 21) was 66.1 degrees—more than 2 degrees warmer than a typical summer in the 1970s, yet nearly 1.5 degrees cooler than a typical summer in the 2020s. In other words, the summer of 2016 would have led to lots of griping had it occurred a half-century earlier—but if the same conditions were to settle in today? We’d consider it cool and refreshing.

 A look at other recent El-Niño-to-La-Niña summers in Seattle reveals similar patterns, with most summers running on the cool side by today’s standards—but not by those of 50 years ago. This includes the summers of 2005, 1998, 1995, and 1988. And then there’s the summer of 2010, where Seattle’s average temperature checked in at 63.6 degrees—almost 4 degrees cooler than the average summer today! Even that summer had its share of scorchers—the mercury topped 90 degrees six times—but it looks downright cool compared to a summer like 2022, when Seattle reached 90 degrees on 13 occasions. In fact, today, the El-Niño-to-La-Niña-transition summer of 2010 stands as Seattle’s second “coolest” summer of the twenty-first century, topped only by the summer of 2001.

Expect a coolish summer. Unless you’ve time-traveled from the 1970s.

The bottom line? If recent history means anything, the temperatures this summer are likely to feel cool to Seattleites—despite the fact that previous generations would have worked up a sweat in similar weather.

Will that make 2024 a cruel summer? That’s for all of us—not just the Swifties—to decide