Hurricane Humberto is set to churn up potentially “life-threatening” surf across parts of the Caribbean this weekend after a day of gathering strength.

Humberto early Saturday was a Category 4 hurricane on the five-step Saffir-Simpson scale, having intensified rapidly on Friday as it hurtled through warm Atlantic waters, according to the U.S. National Hurricane Center.

In a 5 a.m. advisory on Saturday, the center said Humberto was moving slowly west at 6 m.p.h. (10 km/h) and packing maximum sustained winds of 145 miles (233 km) per hour.

Though the storm isn’t forecast to strike land, energy from Humberto is expected to create “life-threatening surf and rip current conditions” on beaches in the northern Leeward Islands, the U.S. Virgin Islands, Bermuda and Puerto Rico this weekend and e

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