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 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 and was moving west-northwest at 10 mph.

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 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.

Another tropical storm, Cosme, formed southwest of Barbara’s position and was posing no threat to land.

Cosme had 45 mph maximum sustained winds late Sunday and may be near hurricane strength Monday, U.S. forecasters said. It was blowing to the northwest at 9 mph and was centered about 650 miles south-southwest of the southern tip of Baja California.