Hurricane Polo’s explosive intensification

In mid-September 2026, Hurricane Polo began as a tropical disturbance off Mexico’s Pacific coast. By September 20, it had organized enough to be classified as a tropical storm. It strengthened further the next day.

Polo then entered a period of exceptionally rapid intensification. Meteorologists used words such as “surprising”, “amazing” and “absolute madness” to describe the storm’s transformation.

“Polo went through what can only be described as an explosive, rapid intensification period,” atmospheric scientist Gary Partica of NASA’s Global Modeling and Assimilation Office at Goddard Space Flight Center said by email. “This was rapid, rapid escalation.”

Partica said Polo encountered “almost perfect” conditions for strengthening: low wind shear, high humidity, warm ocean temperatures and substantial atmospheric instability.

How quickly did Hurricane Polo strengthen?

Several observers described Polo’s development as extreme rapid intensification. The technical classification refers to a tropical cyclone whose maximum sustained winds increase by at least 60 knots—111 kilometers per hour, or 69 miles per hour—in 24 hours.

By September 22, Polo’s maximum sustained winds had reached 90 knots. Within 24 hours, the storm reached Category 5 intensity. The National Hurricane Center described the rate of strengthening as “truly remarkable” in its forecast discussion.

When NOAA hurricane hunter aircraft flew over Polo on September 22, researchers estimated maximum sustained winds near 285 kilometers per hour—about 180 miles per hour.

That intensity made Polo the third-strongest storm on record in the eastern Pacific based on maximum sustained wind speed. Some analysts also identified it as the fastest storm on record to progress from a tropical cyclone to a Category 5 hurricane.

NASA satellite images show Polo’s powerful structure

On the afternoon of September 23, the Moderate Resolution Imaging Spectroradiometer, or MODIS, aboard NASA’s Aqua satellite captured an image of Polo south of Acapulco, off the coast of Guerrero.

At the time, Polo had maximum sustained winds of 230 kilometers per hour, or 145 miles per hour, making it a Category 4 hurricane. An eyewall replacement cycle had weakened the storm slightly.

“The Polo satellite images are very impressive, with the storm’s large, clear eye and extensive outflow pattern,” said Kristen Corbosiero, an atmospheric scientist at the State University of New York at Albany. She is working on a NASA project that uses satellite data to study ventilation in tropical cyclones.

Corbosiero said weak winds above the storm and strong upper-level outflow also helped Polo intensify rapidly.

Why did Hurricane Polo intensify so rapidly?

As Polo developed, it moved across areas where sea surface temperatures reached 32 degrees Celsius, or 90 degrees Fahrenheit. On September 23, those waters were 2 to 3 degrees Celsius warmer than normal.

Most of the region’s surface waters were warmer than 27.8 degrees Celsius, or 82 degrees Fahrenheit—the temperature typically needed to maintain and intensify a hurricane.

The map uses data from NASA’s Multiscale Ultra-high Resolution Sea Surface Temperature project. The MUR SST project combines satellite measurements from NASA, NOAA and international missions with observations from ships and buoys.

Rather than showing absolute temperatures, the map displays temperature anomalies: how much warmer or cooler the ocean surface was on September 23, 2026, compared with the project’s 2003–2014 average for that date.

Corbosiero said that warmer water deeper in the ocean likely helped the storm persist. Hurricanes can churn up cold water from below the surface, which may slow intensification. In Polo’s case, the supply of cold water behind the storm appeared limited.

Measurements and model data showed that ocean heat content remained high at considerable depth.

Is El Niño responsible for Polo’s rapid intensification?

Partica and Corbosiero cautioned against directly attributing Polo’s rapid intensification to El Niño’s unusually warm surface temperatures in the central and eastern Pacific.

Hurricanes in the region have also strengthened rapidly during La Niña events. Corbosiero pointed to neutral conditions during Hurricane Otis in 2023 and Hurricane Patricia in 2015. Both storms reached Category 5 intensity.

However, changes in large-scale ocean and atmospheric circulation patterns typically increase overall tropical cyclone activity in the eastern Pacific during El Niño periods. That pattern has been evident so far in 2026.

As of September 24, accumulated cyclone energy in the region was nearly twice the normal level, according to Colorado State University data.

What happens next to Hurricane Polo?

Researchers and forecasters can track sea surface temperature anomalies and other storm characteristics using NASA’s Worldview browser, the SPoRT near-real-time data viewer and GMAO tools.

Forecasters expected Polo to remain over the Pacific Ocean until the following week before curving northeast toward Baja California.

Images by Michala Garrison using sea surface temperature data from NASA’s MUR project, MODIS data from NASA’s LANCE and GIBS/Worldview, and NOAA storm-tracking data from the National Hurricane Center. Story by Adam Voiland.

Sources

• Colorado State University. Real-time Northeast Pacific statistics by storm for 2026. Accessed September 24, 2026.
• Joint Atmospheric Research Institute. Hurricane Polo. Accessed September 24, 2026.
• Michael Lowry. Polo puts on a show in the Eastern Pacific. Accessed September 24, 2026.
• Forbes. Explosive Hurricane Polo could remain Category 5 for several days. Accessed September 24, 2026.
• NASA Earthdata. Tropical cyclones. Accessed September 25, 2026.
• National Hurricane Center. Hurricane Polo advisory archive. Accessed September 24, 2026.
• Stern, D., et al. Distinguishing between ultra-rapid development and normal rapid development of tropical cyclones. Monthly Weather Review, 154(10), 2133–2149.
• The Washington Post. Hurricane Polo intensifies to Category 5 in less than a day. Accessed September 24, 2026.
• Yale Climate Connections. Tropical Pacific erupts as powerful Hurricane Polo threatens Mexico with heavy rains. Accessed September 24, 2026.