(Adds new location, speed of storm)
MEXICO CITY, Oct 13 (Reuters) - Tropical Storm Octave strengthened south of Mexico's Baja California peninsula on Sunday.
The storm, about 315 miles (505 km) south of the peninsula's tip, was traveling north-northwest at about 13 miles per hour (20 kmph), Miami's National Hurricane Center (NHC) said.
Octave had maximum sustained wind speeds of up to 65 miles per hour (100 kmph) and its strength was expected to fluctuate overnight before gradually weakening on Monday, the NHC said.
There were no hazards affecting land, according to the NHC advisory sent at 2100 GMT. (Reporting by Elinor Comlay; Editing by Jeffrey Benkoe and Leslie Gevirtz)