Tropical Storm Rosa became a Category 1 hurricane off Mexico's Pacific coast Wednesday morning, forecasters said. It is expected to strengthen, but doesn't pose an immediate threat to land.

The U.S. National Hurricane Center (NHC) said the storm was located about 545 miles west-southwest of Manzanillo and about 465 miles south-southwest of the southern tip of Baja California. Rosa's maximum sustained winds increased to about 80 mph and was moving west-northwest at 10 mph.

"Rapid strengthening is forecast to continue through tonight," NHC said in its advisory at 3 p.m. ET. "Afterward, strengthening should continue at a slower rate Thursday and Friday."

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The center predicted Rosa would then gradually weaken because of cooler water and drier air. Warm water is fuel for hurricanes.

Rosa was expected to cause "life-threatening surf and rip current conditions" late this week and over the weekend along the coast of southwestern Mexico and the southern Baja California Peninsula.

NHC said there are no coastal watches or warnings in effect.