U.S. forecasters say Calvin has become the third hurricane of the eastern Pacific season.
The storm had maximum sustained winds of about 75 mph and was moving to the west at 13 mph. It was about 340 miles south-southwest of Cabo Corrientes, Mexico, and did not immediately threaten land.
Calvin was a Category 1 hurricane on Friday. The U.S. Hurricane Center in Miami says the storm is likely to weaken in the coming days, though it could fluctuate occasionally in intensity.