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Climate Shift Index Alert•September 22, 2026

Climate change boosts extreme ocean heat fueling Hurricane Polo

September 22, 2026

On September 22, Hurricane Polo underwent extreme rapid intensification, reaching Category 5 strength with sustained winds of 180 mph off the southwestern coast of Mexico. As of September 23, Polo has weakened to a Category 4 hurricane with sustained winds of 150 mph and is slowly moving northward. 

Heavy rainfall associated with the storm is expected to bring life-threatening flooding and mudslides to coastal communities along southwestern Mexico. The moisture from Hurricane Polo is also increasing the risk of dangerous flooding in the U.S. Southwest.  

Exceptionally warm Pacific sea surface temperatures (SSTs) exceeding 31°C (88°F) helped fuel the storm’s rapid intensification. Human-caused climate change has made these unusually warm ocean temperatures at least 100 to 200 times more likely, significantly enhancing the storm’s potential strength.

2026-09-21-csi-ocean

Note: This is NOT a storm forecast. Visit the National Hurricane Center for the latest updates and information on how the storm is evolving. 

How is climate change influencing this storm?

  • Sea surface temperatures (SSTs) along the path of Hurricane Polo were up to 1.5°C (2.7°F) warmer than they would have been in a world without human-caused climate change.

    • Warmer SSTs are associated with increased risk of rapid intensification.

  • Climate change added at least 6 mph to the storm’s peak sustained wind speed, also known as its lifetime maximum intensity.

    • This calculation is based on preliminary track and data.

  • Over the past several months, the Pacific Ocean has been experiencing a historic and climate-change-driven marine heat wave.

What do experts say?

Dr. Daniel Gilford, Meteorologist and Climate Scientist at Climate Central, said: 

“On top of the ongoing El Niño, human-caused climate change is making the Pacific’s extreme ocean heat much more likely. Hurricane Polo is moving through a region where extreme ocean heat has been building for months, providing the hurricane extra fuel to rapidly intensify into the monster storm it has become.”

To request an interview with a Climate Central expert, please contact Abbie Veitch at aveitch@climatecentral.com.

How do we know climate change is influencing this heat?

The Climate Shift Index: Ocean is grounded in peer-reviewed methodology and high-quality data. It quantifies the influence of climate change on sea surface temperatures.

The Ocean CSI indicates how human-caused climate change has influenced the likelihood of daily sea surface temperatures occurring at nearly any location around the world’s oceans.