Hermine rolled into south Texas as a tropical storm early Tuesday, bringing heavy rains and strong winds to an area battered by Hurricane Alex earlier this summer. Several counties also had to deal with tornado warnings.
Parts of San Antonio saw power outages, flash flood warnings and about a dozen roads closed due to high water.
Hermine left all but one block of Raymondville, about 20 miles off the Texas coast, without electricity and ripped roofs off several buildings.
"It was a lot of wind, a lot of rain coming real fast," said Robert Supulver of Willacy County's emergency operations center.
As many as 30,000 homes were without power in the Rio Grande Valley early Tuesday, according to an online outage map of American Electric Power, the area's power utility.
Hermine made landfall in northeastern Mexico late Monday and crossed into Texas within hours, with swirling winds up to 65 mph. It threatened to dump up to 12 inches of rain in some areas and cause flash flooding.
Tuesday evening Hermine was downgraded to a tropical depression moving north-northwest at about 20 mph with maximum sustained winds of about 35 mph. Tropical storm warnings were canceled by midday.
Mexican emergency officials in Tamaulipas worked to evacuate 3,500 people around Matamoros, across the border from Brownsville, Texas, and schools on both sides of the border canceled classes Tuesday.
Hours after Hermine made landfall, Coast Guard Ensign Scott Kimball said a fishing vessel had run aground at a jetty near South Padre Island.
Neighborhoods lost power while Hermine's center moved over Brownsville, said Joseph Tomaselli, a meteorologist with the National Weather Service. Parts of the Rio Grande Valley still drying out from Hurricane Alex braced for as much as eight inches of more rain.
"It doesn't take a lot of rainfall to cause any flooding down there whatsoever," Tomaselli said.
Tomaselli said remnants of Hermine will be felt as far north as Oklahoma and Kansas in the coming days.
In Mexico, Hermine brought another unwelcome downpour after remnant rains from Alex killed at least 12 people in flooding. In July, Alex caused heavy flooding in the business capital of Monterrey. Damage from the storm was estimated at $700 million.
Mexico's northeast cattle-ranching region is one of the most dangerous hotspots in the country's bloody turf war between two drug cartels. It is the same area where 72 migrants were killed two weeks ago in what it believed to be the country's worst drug gang massacre to date.
Mexican emergency officials urged those living in low-lying coastal areas to move to shelters. Classes in Matamoros and several other Mexican towns were canceled, and authorities began releasing water from some dams to make room for expected rains.
In inland Hidalgo state, authorities said heavy rains caused by the passing storm unleashed landslides that damaged 20 homes, left 120 people homeless and cut off small communities.
The Atlantic hurricane season runs from June 1 through Nov. 30 and is currently in its peak period.