(CNN) -- Tropical Storm Hermine is expected to cross into Texas on Tuesday after striking the Mexican coast about 40 miles south of the U.S. border Monday night, the National Hurricane Center reported.
The storm is expected to dump four to eight inches of rain over northeastern Mexico and sections of southern and north-central Texas. Isolated amounts of up to 12 inches are possible, according to the hurricane center.
The heavy rains could cause life-threatening flash floods, forecasters warned.
Texas authorities already have blamed a Houston woman's drowning Sunday night on the storm.
Galveston Island Beach Patrol Chief Peter Davis said a friend reported that 44-year-old Veronica de Leon Jaure had stepped off a sandbar into a trough and disappeared into a current. The friend searched for half an hour before calling police, Davis said.
Hermine brought rough waters to Texas beaches throughout the Labor Day weekend. Davis said his agency rescued 18 people over the weekend, including four on Monday.
At 11 p.m. ET Monday, Hermine was located about 30 miles south of Brownsville, Texas, and was packing maximum sustained winds of 60 mph (95 km/h). The storm was moving north-northwest at 14 mph (22 km/h).
"A gradual turn toward the north and northeast is expected over the next couple of days," the hurricane center said.
The agency predicts Hermine will move into southern Texas on Tuesday and into central Texas early Wednesday.
CNN's Sean Morris and Dave Alsup contributed to this report.