MEXICO CITY (AP) — Tropical Storm Barbara was strengthening off Mexico's Pacific coast and could become a hurricane Monday, forecasters said.

Barbara was centered about 235 miles (375 kilometers) west-southwest of the touristic port of Zihuatanejo in Guerrero state late Sunday, according to the U.S. National Hurricane Center in Miami. It had maximum sustained winds of 65 mph (100 kph) and was moving west-northwest at 10 mph (17 kph).

The storm was forecast to remain at sea, though heavy rainfall may cause localized flooding and mudslides on Mexico's western coast. Around 2 to 4 inches (5 to 10 centimeters) of rain are possible across portions of Guerrero, Michoacan, Colima, and Jalisco states through Monday.

Swells affecting portions of the southwestern Mexico coast for the next few days could produce life-threatening surf and rip current conditions, the hurricane center said.