Hurricane Polo is a strong Category 3 storm off Mexico. See its path.

Hurricane Polo was downgraded to a Category 3 storm as its intensity fluctuated hundreds of miles off Mexico’s southwestern coast on Saturday. 

The storm still remains a major hurricane, the Miami-based National Hurricane Center said in an update Saturday night, and it is expected to make landfall in Baja California on Monday. A hurricane warning is in effect for a stretch of northwestern Mexico and the southwestern U.S. from Punta Abreojos in Baja California Sur to Santa Fe, New Mexico.

The storm had maximum sustained winds of 120 mph. Hurricane-force winds were extending outward up to 40 mph from the center of the storm, while tropical storm force winds extended outward up to 160 mph. The storm was inching slowly northwest. 

Elsewhere in the Pacific, Nolo strengthened into a hurricane as it moved past Hawaii’s Big Island this weekend, bringing heavy rain to Hawaii’s Big Island.

Maps show Hurricane Polo’s projected path

Polo’s core on Saturday was about 335 miles south-southwest of Cabo San Lucas at the tip of the Baja California peninsula. It was heading northwest at 10 mph.

The storm is expected to move north on Sunday. By Monday, Polo is forecast to turn northeast and make landfall in Baja California Sur and then move across northwestern mainland Mexico by Tuesday. 

The State Department, citing forecast models, said the storm is expected to weaken to a Category 1 storm before making landfall. It will then continue northeast into southern Sonora, the State Department said. The hurricane center noted, however, that despite weakening, Polo is still expected to be a “strong hurricane” when it reaches Baja California Sur. 

Polo could produce 4 to 8 inches of rain, and up to 10 inches in isolated areas, across parts of Baja California Sur, the hurricane center said, cautioning the rain “may produce life-threatening flooding and mudslides, especially in areas of steep terrain.”

Along with the hurricane warning, both a hurricane watch and tropical storm warning were also in place for the west coast of Baja California Sur from Punta Eugenia to Punta Abreojos. A hurricane watch was in place for the east coast of Baja California Sur from Bahia San Juan Bautista to San Evaristo.

Polo-generated swells will affect the southwestern Mexican coast over the next couple of days, spreading north along the west-central coast and the Baja California peninsula through the weekend, the hurricane center said, warning that swells are “likely to cause life-threatening surf, rip currents, and coastal flooding.”

Mexican leaders ordered evacuations, opened shelters and deployed military troops to areas that could be affected by the storm.

Classes were suspended at schools across the city of Acapulco, along the coast of Guerrero, its municipal government announced. Shelters across the state remained open, and officials said they were coordinating with local and national authorities to prepare for additional impacts of the hurricane.

Polo’s extreme rapid intensification

Polo underwent what’s called extreme rapid intensification, in which a storm’s wind speeds increase by 58 mph or more over the course of 24 hours, between Sept. 21 and Sept. 22.

Its intensification was dramatic even by those standards, with winds that skyrocketed from 45 mph on the morning of Sept. 21 to 150 mph at around the same time the following day. The hurricane center described the storm’s transformation as “truly remarkable.”

Its maximum sustained winds climbed as high as 180 mph at one point, far exceeding the 157 mph threshold for Category 5, the strongest on the hurricane scale. By Saturday morning, the maximum sustained winds had lowered to near 160 miles per hour, with some higher gusts. 

Polo’s central pressure — an indicator of its strength and potential destructiveness — made it the second-strongest hurricane on record in the Eastern Pacific, behind 2015’s Hurricane Patricia. The storm’s wind speeds tied 2009’s Hurricane Rick as the third-strongest on record for the region.

Unusually strong El Niño conditions this year have been amping up tropical cyclone activity in the Pacific, with warmer waters, moist air and less wind shear enabling storm formation.