A dog wades through a flooded street next to a battered house after Hurricane Jimena hit Puerto San Carlos. (Henry Romero/Reuters)

Heavy rain pounded down on Mexico's Baja California peninsula Thursday as tropical storm Jimena moved through the region.

Jimena, a once-powerful Category 4 hurricane, was further downgraded to a tropical storm on Wednesday as it moved along the peninsula's eastern coast.

"The biggest threat with Jimena is heavy rainfall causing flash floods and mudslides," said the U.S. National Hurricane Center.

At 11 a.m. ET, Jimena was centered about 75 kilometres northwest of Santa Rosalia, Mexico, and was moving northwest near 7 km/h, according to the U.S. National Hurricane Center.

Tropical storm warnings were in effect for the west coast of the Baja California peninsula from Puerto San Andresito northward. The warnings were expected to be lifted by the end of the day.

A man carries belongings as the eye of Hurricane Jimena is about to pass over Puerto San Carlos. (Henry Romero/Reuters)

The storm made landfall Wednesday afternoon as a Category 1 hurricane between Puerto San Andresito and San Jaunico, a sparsely populated area of fishing villages on the Pacific coast of the peninsula. It skirted the peninsula's main resorts and then weakened to a tropical storm.

Jimena could weaken to a tropical depression by Thursday night, the hurricane centre said.

The forward motion of Jimena is also expected to stop late Thursday with the storm moving more inland before dissipating within the next 96 hours, the centre said.

Jimena is expected to bring up to 130 millimetres of rain to parts of the peninsula. Officials said the heavy rains might help alleviate the drought in much of northwest Mexico.

"Fortunately, this kind of weather phenomenon we're going through transports a lot of water," national water commissioner Jose Luis Luege Tamargo said on the radio. "This rain undoubtedly will fill up the aquifers of the whole region."

Higher than normal tide levels and large waves are also forecast along the coast for the next two days.

At the height of the storm, wind gusts and heavy rains blew down dozens of trees and lampposts in Loreto, near where Jimena made landfall.

Similar damage was being reported in the small farming city of Ciudad Constitucion, where there were also reports of roofs having blown off homes.

With files from The Associated Press