The Hollywood sign stands sentinel above Los Angeles, watching the volcano dance like disoriented stars throughout the January night. Glowing debris floats in the warm air past million-dollar mansions, while emergency crews battle fires that shouldn't exist — not in winter, not here, not now.
Two thousand miles to the east, in the heartland of America, a different emergency is unfolding. The mercury plunges to depths not seen in a decade. Wind chills reach the low 40s. Airlines ground flights by the hundreds. Roads become treacherous ribbons of ice. People huddle in warming centers while the polar air howls outside like a hungry ghost.
Fire and ice. A nation divided into two.
We've been here before. The winter of 2013-14 wrote the first dramatic chapter in this story. California is facing its worst drought in 1,200 years — a drought so severe that America's fruit baskets are wilting on the vine. Meanwhile, the eastern United States was rocked by what the media dubbed the “reversion of the polar vortex.” The temperature fluctuation between California and the East Coast is unlike anything we've seen in modern records.
That winter changed the way we think about climate. At Utah State University, Our research revealed something fascinating: the atmosphere behaved like a river facing a boulder. Just as water creates waves when it flows around obstacles, our atmosphere creates waves when it encounters mountain and ocean heat patterns. These aren't just waves—they're massive atmospheric ripples that can span continents.
Think of the jet stream—the river of air flowing high above our heads—as a cosmic garden hose. When it is straight, weather patterns move normally. But lately, something has shaken it up quite dramatically. A previous study Found the culprit: The western Pacific Ocean is warming significantly, creating an atmospheric domino effect that reaches as far as North America.
Here's how it works: That warm western Pacific acts like a hot plate beneath the atmosphere, creating rising winds that send waves eastward, like dropping a stone in a pond. These waves travel through the jet stream – a cosmic highway for these atmospheric disturbances. When these waves reach North America, they can become “stuck” in a particular system, creating persistent extreme weather along both coasts or along one coast and the Midwest.
By 2017, we saw another manifestation of this model, but with a twist. California swung dramatically From drought to flood Atmospheric rivers — literal rivers of water vapor in the sky — hit the state. Then in January 2018, the eastern US plunged into another deep freeze, while the west remained stubbornly hot and dry. The pattern was more pronounced, and more persistent.
The evidence for this proliferation is not just anecdotal. Our study These winter climate extremes have shown an approximate 20% increase in strength since the late 20th century. We can actually see it in the form of the jet stream, which now turns into deeper waves than it did a few decades ago. It's like a river that once flowed relatively straight, and began to meander wildly.
The physics behind this is clear. The warming of the western Pacific Ocean is not a random fluctuation; It is part of a larger pattern of climate change. This warming creates strong “wave trains” of atmospheric energy, which propagate toward North America via the jet stream. When these waves interact with our mountains and existing weather patterns, they create this continuous seesaw effect between the coasts.
Now, in 2025, we see the same pattern playing out again, but with even greater intensity. The Palisades fire has become the most destructive winter fire in Los Angeles' history, while the eastern United States faces its most significant winter storm in a decade. This is not a coincidence. The same atmospheric pattern we've been tracking for years flexes its muscles with unprecedented strength.
The changes we see are no longer subtle. Our latest study A specific atmospheric fingerprint has been identified that is becoming more frequent and more intense across the western United States. It's a unique three-part wave in the atmosphere that creates the perfect conditions for fires, and has been frequent since the 1980s, driven by warming in the subtropical eastern Pacific Ocean.
This pattern, known as a weather regime, does something insidious to the landscape: It dramatically increases the atmosphere's thirst for moisture. As this weather pattern changes, the lack of precipitation worsens the drought: the atmosphere itself pulls water from the soil, from the plants, from everything, turning California's landscape into a tinderbox. method Can last for weeks, creating fire conditions even in the wettest, coldest part of the year.
Particularly dangerous is how this method reinforces itself. As land dries, it heats up more easily, strengthening the atmospheric ridges that caused the drying in the first place. It's a vicious cycle that turns winter into an extension of the fire season. In 2014, this pattern was so intense that NASA satellites could see the mountains of California rising because the weight of the water was literally lifted off the landmass.
But understanding these patterns gives us power. We got caught in 2014. By 2017, we were better prepared, although the intensity surprised us. Now, with 5 million Californians under red flag warnings and 60 million easterners facing winter storm warnings, at least we can see it coming. Weather forecasters can warn communities days in advance. Emergency managers can deploy resources before they are needed. Communities can prepare.
The question is not whether these methods will continue; Our research shows that they do. The question is how do we write the next chapter, how do we adapt to this new normal without a fire season unknown calendar?
Robert Frost once thought the world would end in fire or ice. This winter, America doesn't have to choose. Understanding the new patterns of our climate doesn't make them any less dramatic, but it does give us a fighting chance to prepare for what comes next.
Shih-Yu Simon Wang is a professor of climate science at Utah State University.