Hawaii is under a state of emergency with powerful Hurricane Lowell set to bear down on its western islands Monday. It’s the third storm in as many weeks to threaten the state, as El Niño supercharges the Pacific hurricane season.

The hurricane was a Category 4 with winds up to 150 mph early Saturday morning, local time, according to the National Hurricane Center, as Lowell fluctuates between Category 4 and 5 strength.

“Some additional intensification is possible over the next day or so, followed by a gradual weakening trend by early next week,” the center said. Lowell is forecast to be near Category 4 strength when it approaches Hawaii. Just how bad the hurricane gets for the island chain hinges on how close it tracks to its westernmost islands of Niihau and Kauai early next week.

A shift of less than 100 miles east of its current forecast track would mean more direct impacts from a potential major hurricane. Dangerously rough seas, coastal flooding and rip currents are likely, especially for the western islands, even if that shift doesn’t happen.

Hawaii Gov. Josh Green declared a state of emergency for the entire state on Thursday to free up state resources and activate Hawaii National Guard units. Six high-water vehicles are also being deployed to Kauai, he said.