Hilary, a small but powerful storm, strengthened to a Category 4 hurricane late on Thursday as its core continued to move parallel to the southwest Pacific coast of Mexico.

The storm was 85 miles southwest of the popular resort of Acapulco, packing maximum sustained winds of 135 miles per hour, the Miami-based National Hurricane Center said.

“Some additional strengthening is possible on Friday. There will be some fluctuations in intensity during the next day or so,” forecasters added.

Hilary, now on the fourth rung of a five-step severity scale, is the seventh hurricane of the Pacific season. None has caused major damage so far.