MIAMI -- Hurricane Sandra has weakened slightly but is still a powerful Category 3 storm in the eastern Pacific off Mexico's coast.

The hurricane's maximum sustained winds Thursday afternoon were 120 mph (195 kph). The U.S. National Hurricane Center says rapid weakening is expected: Sandra is forecast to weaken to a tropical storm Friday night and become a remnant low on Saturday.

Sandra is centred about 380 miles (610 kilometres) south of the southern tip of Mexico's Baja California peninsula and is moving north near 12 mph (19 kph).

A tropical storm watch is in effect for the Baja California peninsula from Todos Santos to Los Barriles.