Hurricane Blanca strengthened to a category four storm Saturday as it barreled toward Mexico, although forecasters said it could weaken before making landfall on the Baja California peninsula.

At 1800 GMT, Blanca was moving northwestward at 17 kilometers (11 miles) per hour, the US National Hurricane Center (NHC) said. It was located 540 kilometers south of Cabo San Lucas.

After briefly weakening Friday, the storm was packing powerful sustained winds of 215 kilometers per hour, with higher gusts.

A hurricane watch was in effect for Cabo San Lucas to Santa Fe along the coast, while a tropical storm warning was in effect from La Paz to Santa Fe, including Cabo San Lucas.

There was also a tropical storm watch from north of La Paz to San Evaristo, and north of Santa Fe to Cabo San Lazaro.

A turn toward the north-northwest was forecast for late Saturday.

The eye of the storm was expected to be near the southwest coast of Baja California Sur in the warning area late Sunday, the Miami-based NHC said, predicting some weakening beginning that day.

It forecast some weakening starting Sunday.

Blanca was expected to bring torrential rains and hail.

The storm could produce up to 25 centimeters (10 inches) of rain over much of Baja California Sur and the southern portion of Baja California state, and up to 38 centimeters in isolated areas over Baja California Sur.

"Tropical storm conditions are expected to first reach the warning area on Sunday, making outside preparations difficult or dangerous," the NHC said, with hurricane conditions possible in the hurricane watch area.

Along the coastline, swells generated by Blanca are "likely to cause life-threatening surf and rip current conditions," the center added.

In September, the resort of Los Cabos, with about 240,000 residents and popular with American tourists, suffered the brunt of Hurricane Odile, which left six people dead and caused massive property damage.