A Texas man has appeared in court charged with the murder of his ex-wife, who disappeared just before Hurricane Harvey made landfall.

Police said Steven McDowell, 44, confessed to strangling Crystal Seratte McDowell, 37, to death in the lounge room of his home on August 25. Their children, aged 5 and 8, were in the next room.

Crystal McDowell, a realtor, had been divorced for three months and was staying with her boyfriend of three weeks, Paul Hargrave, when she went to her ex's house to pick up the children, according to CBS.

She was last seen on Hargrave's surveillance footage getting into her black Mercedes Benz. She was reported missing the next day.

"She had mentioned that she was going to stay at the house, the ex-husband's house, with the kids or, depending on traffic and how weather conditions were, she was going to take them out," Hargrave said.

McDowell told relatives that his ex-wife had texted him saying she planned to go to Dallas with the kids, according to CBS.

Four days later, after Harvey made landfall, Crystal McDowell's car was found in a motel car park about 11km from her house.

Detectives said there was "some real possibility" her disappearance was planned to coincide with the hurricane, according to People.

Her body was found two weeks later when police traced her mobile phone to a marsh in Texas.

Chambers County Sheriff Brian Hawthorne told the Houston Chronicle that they don't yet know the motive in the slaying. He told the Baytown Sun that early indications show McDowell was strangled, but the autopsy report is not yet back.

Steven McDowell is being held on US$500,000 ($690,000) bond. He wept in court on Wednesday (US time).