GUAYMAS, Mexico – September 29, 2026 – Hurricane Polo reached Mexico’s northwestern state of Sonora on Tuesday, making a second landfall near the coastal city of Guaymas as a Category 1 hurricane after crossing the Gulf of California from Baja California Sur.
The storm was already a much weaker system than the powerful hurricane that had approached the Baja California peninsula.
Polo made its first landfall in Baja California Sur as a Category 2 hurricane, with maximum sustained winds of around 110 mph (175 km/h). By the time it approached mainland Mexico, its sustained winds had fallen to about 75 mph (120 km/h).
Polo’s weakening marked the final stage of a remarkable journey that had taken the storm from the tropical eastern Pacific, across Baja California Sur and then over the Gulf of California before reaching the mainland.
A Hurricane Over the Desert
The arrival of a hurricane in Sonora may seem surprising. The state is home to much of the Sonoran Desert, one of North America’s hottest and driest desert regions. But the apparent contradiction is largely a matter of geography.
Sonora has a long coastline along the Gulf of California, also known as the Sea of Cortez. While the landscape immediately inland is arid, the storm itself is moving over an ocean environment capable of supplying enormous amounts of heat and moisture.
Tropical cyclones are fueled by warm ocean water. NOAA notes that sea-surface temperatures of around 26.5°C (80°F) or higher are generally needed to support tropical cyclone development and intensification.
The Gulf of California can therefore provide an important source of tropical moisture even as the surrounding landscape becomes increasingly desert-like. And the contrast is striking: a tropical cyclone can move over some of the driest terrain in North America while still carrying a huge reservoir of moisture from the sea.
The Gulf of California factor
Polo’s path also illustrates why the Gulf of California can matter so much to tropical systems approaching northwestern Mexico.
A storm crossing Baja California Sur must spend some time over land, which normally disrupts the circulation and weakens the system. Polo did indeed lose strength after crossing the peninsula.
But its next environment was very different. Instead of continuing over dry land, the storm emerged over the Gulf of California and headed northeast toward Sonora.
The National Hurricane Center expected Polo to remain a tropical cyclone as it crossed the gulf before reaching the mainland.
This is not unprecedented. In previous storms, the National Hurricane Center has noted that the warm waters of the Gulf of California can help a tropical cyclone maintain its characteristics after crossing Baja California.
The gulf therefore acts as a narrow corridor of warm, moisture-rich air between the Baja California peninsula and mainland Mexico.
A Desert Can Still Flood
The most immediate threat from a storm like Polo is not necessarily the wind. It is the water. The National Hurricane Center forecast 4 to 6 inches (100-150 mm) of rain across southern and central Sonora, with isolated totals of up to 8 inches (200 mm).
Such rainfall is capable of producing life-threatening flooding and mudslides, particularly in mountainous terrain. That may sound modest compared with rainfall totals associated with some tropical cyclones elsewhere.
But in an arid environment, several inches of rain arriving in a short period can overwhelm normally dry washes, streams and drainage channels.
The National Weather Service has repeatedly documented the same phenomenon across the Sonoran Desert and the wider U.S. Southwest: tropical moisture arriving from the Gulf of California can dramatically increase rainfall potential, while hard or rocky ground and intense rainfall rates can produce rapid runoff and flash flooding.
In other words, a desert does not make a tropical storm harmless. In some circumstances, it can make sudden rainfall even more hazardous.
Polo’s Final Act
By the time Polo reached Sonora, the storm was already approaching the end of its life as a hurricane.
Mexican meteorological authorities reported the center just south of Guaymas with sustained winds of about 120 km/h (75 mph) and gusts reaching 150 km/h as it approached the coast.
After making its second landfall, Polo rapidly weakened as it encountered the rugged terrain of northern Mexico.
The storm’s tropical remnants were then expected to continue northeast toward the U.S. Southwest, carrying significant tropical moisture with them.
The U.S. Weather Prediction Center warned that the remnants could contribute to heavy rainfall across parts of Arizona, New Mexico, Texas and the central Plains.
Polo’s story therefore ends far from the warm tropical waters where it began – not with a dramatic final strike, but with a gradual transformation from hurricane to tropical storm and eventually into a broader rain-producing weather system.
Yet its final passage is a reminder of something that can be easy to forget when looking at a desert landscape: Deserts may be defined by a lack of rainfall, but they are not immune to extreme rainfall.
When a tropical cyclone carries the ocean inland, even one of the driest regions of North America can suddenly become a landscape of swollen rivers, flash floods and mudslides.
Sources:
- NOAA / National Hurricane Center – official advisories, track and intensity information for Hurricane Polo.
- Mexico’s National Water Commission (CONAGUA) – official meteorological information and rainfall forecasts for Baja California Sur and Sonora. (Gobierno de México)
- U.S. National Weather Service / Weather Prediction Center – rainfall and flash-flood assessment associated with Polo and its remnants. (National Weather Service)
- NOAA Atlantic Oceanographic and Meteorological Laboratory – explanation of the role of warm ocean water in sustaining tropical cyclones. (aoml.noaa.gov)
- Reuters – reporting on Polo’s second landfall near Guaymas and its weakening over northwestern Mexico. (Reuters)
- Associated Press – reporting on Polo’s landfall in Baja California Sur, subsequent weakening and impacts in Mexico and the U.S. Southwest. (AP News)
- Hurricane Rachel – Tropical Cyclone Warning No. 20: xviii.comondu.gob.mx
