But the National Hurricane Center in Miami said in its 8 p.m. PDT advisory that Octave was expected to weaken rapidly as it approaches the southern Baja California Peninsula.
Octave, which was pushing tropical storm-force winds out up to 45 miles from its center, was about 215 miles northwest of Socorro Island and about 290 miles west-southwest of the southern tip of Baja California as it headed to the north-northwest at 15 mph, the forecasters said.
The hurricane center said there were no coastal watches or warning in effect, though it urged those with interests in the region to monitor the storm's progress.
Octave, which had 45 mph winds when the hurricane center announced its formation at 2 a.m. Sunday, is expected weaken and slow down during the next two days, becoming a remnant low pressure area by later Tuesday.
The storm is forecast to turn to the north Monday and veer to the north-northeast Tuesday.