Sept. 1 (UPI) — Karina strengthened into a major Category 4 hurricane Monday and was moving west into the open waters of the Pacific Ocean, forecasters said.

The hurricane had maximum sustained winds of 130 mph and was located about 1,135 miles west-southwest of the southern tip of Baja California in northwestern Mexico, the National Hurricane Center said in its 5 p.m. HST update.

It was moving west-northwest at 9 mph. Hurricane-force winds extend outward up to 30 miles, according to the NHC, a large increase over the 5 mph radius a day earlier.

Forecasters said the storm is expected to take a slower westward to west-northwest motion over the next few days, with some additional strengthening possible.

Swells generated by the storm are forecast to affect the coast of southwest Mexico and the Baja California Peninsula during that time, according to the NHC, which warned that they are likely to cause life-threatening surf and rip current conditions.