Hurricane Agatha, the first of the Pacific season, left nine people dead and six missing after slamming into southern Mexico, fewer than previously thought, authorities said Thursday.

Agatha barreled ashore on Monday near Puerto Angel in Oaxaca state as a Category Two hurricane, the second lowest on a scale of five, causing flooding, landslides and damage to homes.

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

"We have nine officially confirmed deaths and six people still missing," Oaxaca governor Alejandro Murat told reporters.

The previous day he had reported 11 dead and 22 missing based on preliminary information.

The toll was revised after communication and access was restored to remote mountain communities.

A man clears a street in Huatulco in southern Mexico after Hurricane Agatha triggered heavy rains and mudslides
A man clears a street in Huatulco in southern Mexico after Hurricane Agatha triggered heavy rains and mudslides AFP / Gil OBED

"The inhabitants of Oaxaca affected by this hurricane are not alone," President Andres Manuel Lopez Obrador said.

"We're going to support them, so that the roads are restored, so that the services are improved," he told reporters.

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

On Thursday the remnants of Agatha were located over Mexico's Yucatan Peninsula, home to major Caribbean beach resorts.

The country's meteorological service said there was an 80 percent chance of a new storm forming within the next five days.