Hurricane Polo rocketed from a tropical storm to a Category 5 system in less than a day on Tuesday, with peak winds of 180 mph before easing to Category 4 while drifting off Mexico’s southwest coast, according to the National Hurricane Center. The agency called Polo a very powerful major hurricane in an update issued Wednesday.
As the cyclone tracks northwest, forecasters expect torrential rain along portions of the Mexican Pacific coast. While a direct landfall is not currently projected, officials warned that heavy precipitation could trigger life-threatening flooding and mudslides, and that marine conditions will be extremely dangerous.
Hurricane Polo and El Niño’s influence
Rapid strengthening of tropical cyclones occurs several times a year globally when the right ingredients align, according to Julian Heming, an environmental scientist at the U.K. Met Office. He cited very warm ocean temperatures, low vertical wind shear and supportive upper-atmosphere outflow as key factors.
Polo intensified while passing over exceptionally warm Pacific waters linked to an extremely strong El Niño that has persisted since June. El Niño develops when the eastern tropical Pacific becomes abnormally warm, alongside shifts in winds, surface pressure and rainfall. U.S. climate officials define El Niño conditions when sea surface temperatures in that region are at least 0.5 degrees Celsius, or 0.9 degrees Fahrenheit, above average, accompanied by those atmospheric changes.
Events are categorized by strength from weak to very strong. Although not a formal scientific label, the term super El Niño commonly refers to very strong episodes in which sea surface temperatures exceed 2 C above normal.
Heming said the unusually warm sea provided ample heat and moisture, while very moist air aloft and weak upper-level winds allowed thunderstorms to organize and intensify with minimal disruption. Polo also formed a compact, well-defined core that concentrated energy into a small area, enabling exceptional rapid intensification. Together, these elements functioned as an efficient atmospheric heat engine.
“Polo’s rapid and sudden growth is testament to the dominance of this year’s so-called super El Niño,” Heming said, adding that the pattern has amplified numerous extreme weather events worldwide.
Recent assessments from the World Meteorological Organization indicate the current El Niño could be the strongest on record and may last until at least February 2027. Prolonged El Niño conditions can drive more extremes, pushing some regions toward drought while others face stronger storms, heavier rainfall and flooding.
If Polo’s track shifts north, Southern California could see periods of intense rain, and coastal areas may encounter large swells and hazardous rip currents. However, Heming noted substantial uncertainty remains over whether the storm will curve farther out to sea or turn northeast toward Mexico.
Prolonged El Niño conditions can drive more extremes, pushing some regions toward drought while others face stronger storms, heavier rainfall and flooding.
Recent assessments from the World Meteorological Organization indicate the current El Niño could be the strongest on record and may last until at least February 2027. Prolonged El Niño conditions can drive more extremes, pushing some regions toward drought while others face stronger storms, heavier rainfall and flooding.
If Polo’s track shifts north, Southern California could see periods of intense rain, and coastal areas may encounter large swells and hazardous rip currents. However, Heming noted substantial uncertainty remains over whether the storm will curve farther out to sea or turn northeast toward Mexico.