The hurricane was forecast to continue strengthening and could be a major hurricane as soon as Tuesday night or Wednesday morning. A major hurricane is classified as Category 3 or higher, with maximum sustained winds of at least 111 mph (180 kph).
Flossie was moving to the northwest at 7 mph (11 kph) and was expected to generally continue that motion over the next few days. The system should move away from southwestern Mexico by Tuesday night, forecasters said.
A tropical storm warning was in effect from Punta San Telmo to Playa Perula. Rainfall totals up to 6 inches (15 centimeters) were possible in some areas, the hurricane center said.
Forecasters expect Flossie to weaken starting late Wednesday.