Hurricane Harvey has weakened since it hit South Texas in the US head-on late Friday but meteorologists are noting a pattern in which the system appears to remain in one area over multiple days, according to media reports.

The eye of the hurricane reached land by 11 pm ET between Port Aransas and Port O'Connor, Texas, with winds of more than 130 mph, CNN reported.

Harvey was downgraded to a still-dangerous Category 2 hurricane around 4 am ET when winds dropped to 110 mph, the National Hurricane Center said.

It was the first Category 4 hurricane to make landfall in the US since Hurricane Charley in 2004, the report said.

Millions of residents along the south Texas coast saw hurricane-force winds that knocked down trees, power poles and signs.

Forecasters have said the impact of the hurricane will be devastating and leave areas "uninhabitable for weeks or months."