The summer of 2025 will be remembered as a turning point in how we understand extreme weather in the United States. This article explores how a dramatically disrupted polar jet stream triggered deadly flash flooding across the central and eastern U.S.—especially in Texas and Kentucky—while simultaneously steering all major hurricanes away from the mainland.
We will look at the atmospheric mechanics behind these events, the role of climate change in reshaping the jet stream, and what this means for future risks to communities and ecosystems.
The Summer 2025 Floods: A New Kind of Extreme
In 2025, flash flooding across central and eastern U.S. reached an intensity and scale that far exceeded historical norms. Hundreds of lives were lost, and infrastructure damage ran into the billions, with Texas and Kentucky among the hardest-hit regions.
These floods were not simply “bad luck” or isolated anomalies. They were driven by a persistent, unusual pattern in the atmosphere that allowed storms to linger over the same locations for days, unleashing relentless rainfall.
How a Stalled Jet Stream Supercharged Rainfall
The central player in this story is the polar jet stream, a fast-moving ribbon of air high in the atmosphere that normally guides weather systems across North America. In summer 2025, the jet stream behaved in ways we rarely see.
Instead of flowing in a relatively smooth, west-to-east path, the jet stream:
This combination caused storm systems to slow down or stall. When storms stop moving, rainfall accumulates over the same area, dramatically increasing flood risk.
What might have been a moderate storm in a fast-flow regime became a catastrophic multi-day deluge in a sluggish, wavy jet stream pattern.
Moisture from the Gulf: Fuel for Extreme Storms
The jet stream’s unusual path also tapped into an abundant supply of moisture. Its southward dip acted like a conveyor belt, drawing humid air from the Gulf of Mexico deep into the interior United States.
This moisture feed was intensified by warmer Atlantic and Gulf waters, which increase evaporation and load the atmosphere with more water vapor. When lifted by storm systems, this moisture condensed into heavy rainfall, significantly boosting the intensity of each event.
Adding to the problem, persistent high-pressure systems flanked the region, effectively locking the jet stream—and therefore the storms—in place.
The result was repeated rounds of heavy rain over the same states, producing catastrophic flash flooding.
Why Hurricanes Missed While Floods Hit
In a striking contrast, the 2025 hurricane season in the Atlantic featured five hurricanes that all curved away from the U.S. mainland. This unusual outcome was not coincidence; it was tied to the same jet stream disruptions.
The Steering Role of the Jet Stream and Atlantic High
Hurricanes are steered by large-scale atmospheric features, including the polar jet stream and subtropical high-pressure systems over the Atlantic. In 2025:
While inland communities suffered devastating floods from stalled storm systems, coastal regions were spared landfalling hurricanes.
Climate Change and a Distorted Jet Stream
The underlying driver of these jet stream anomalies is increasingly clear: human-driven climate change. Warming is not uniform across the globe; the Arctic is heating up faster than the mid-latitudes, shrinking the temperature contrast between the equator and the pole.
From Strong, Straight Jet to Slow, Wavy Jet
The polar jet stream is powered by the temperature gradient between warm and cold regions. As Arctic warming weakens this gradient, the jet stream tends to:
These exaggerated “planetary waves” in the jet stream are associated with prolonged extreme events—whether heat waves, droughts, or persistent storms.
Studies now show that such amplified patterns are roughly three times more common than in the 1950s, a profound shift over just a few generations.
Looking Ahead: Rising Risks in a Warming World
As global warming continues, we should expect more frequent and more intense disruptions of the jet stream.
For societies and ecosystems, this means:
Understanding the jet stream is no longer an abstract academic exercise.
It is central to anticipating and managing the new era of climate-driven extremes that societies are now entering.
Here is the source article for this story: 2025’s extreme weather had the jet stream’s fingerprints all over it, from flash floods to hurricanes