Hurricane Agatha, the first of the season, lashed a string of beach resorts on Mexico's Pacific Coast as it barreled ashore Monday, bringing strong winds, heavy rain and flood warnings.

Agatha was the strongest storm to make landfall along Mexico's Pacific coast in May since record keeping began in 1949, the US National Hurricane Center (NHC) said.

It touched land near Puerto Angel in the southern state of Oaxaca as a Category 2 hurricane -- the second lowest on a scale of five.

Agatha later weakened to a Category 1 storm, but still packed maximum sustained winds of 130 kilometers (80 miles) per hour, the NHC said.

"Rapid weakening is expected as the hurricane moves farther inland. Agatha is forecast to weaken to a tropical storm tonight, and dissipate over southeastern Mexico by late Tuesday," it said.

Small landslides were reported in parts of Oaxaca, civil protection coordinator Oscar Valencia told the Milenio television channel.

Residents along the coast had stocked up on food and water and boarded up windows of homes and businesses as Agatha approached.

Seaports in the area closed and airlines canceled flights to the region.

Authorities opened around 200 storm shelters with room for up to 26,800 people, while hotels provided refuge to the estimated 5,200 national and foreign tourists in the danger zone.

"We are already on red alert. This is coming and it is coming strong," Roberto Castillo, a civil protection official in Huatulco, told AFP as the storm neared.

A hurricane warning was issued for a stretch of coastline including Puerto Escondido and other surf towns popular with Mexican and foreign tourists, leaving normally busy beaches deserted.

"Storm surge is expected to produce extremely dangerous coastal flooding" and will be accompanied by "large and destructive waves," the NHC said.

"Agatha will produce heavy rains over portions of southern Mexico through Tuesday night," as well as "life-threatening surf and rip current conditions," it predicted.

In Oaxaca and neighboring Chiapas state, "life-threatening flash flooding and mudslides may occur," the NHC added.

The region is home to several major rivers and Mexico's meteorological service warned of possible overflows and landslides.

Mexico is regularly lashed by tropical storms on both its Pacific and Atlantic coasts, generally between the months of May and November.

The deadliest storm to hit Mexico last year was a Category 3 hurricane called Grace that killed 11 people in the eastern states of Veracruz and Puebla in August.