Rain was beginning to fall on Mexico's west coast from Dalila, the fourth named storm of the Pacific hurricane season, which was gaining strength as it approached land, officials said Sunday.

"The center of Tropical Storm Dalila is gradually approaching the Michoacan and Colima coast, moving slowly toward the north-northwest," the Mexican National Meteorological System said in its latest report.

Meanwhile, the US National Hurricane Center in its latest advisory said the "outer rainbands of Dalila (were) beginning to move onshore" in southwestern Mexico.

Although the center of the tropical cyclone was expected to remain offshore, the Miami-based center warned "Dalila is still expected to produce tropical storm conditions within the warning area on Monday."

"Gradual strengthening is expected during the next 48 hours, and Dalila could become a hurricane on Tuesday," it said.

At 0300 GMT, the storm was located about 150 miles (245 kilometers) south of the coastal tourist town of Manzanillo, Mexico, with maximum sustained winds of 45 miles (75 kilometers) per hour.

It was moving to the northwest at 10 miles (17 kilometers) per hour.