Some of the wave energy will come from Tropical Storm Aletta, which reached hurricane strength off the west coast of Mexico last week.
The U.S. National Hurricane Center said Bud had maximum sustained winds of 115 miles per hour (185 kph) Monday morning.
The NHC issued a tropical storm watch for Manzanillo to Cabo Corrientes, meaning tropical storm conditions are possible there over the next day. According to the NHC, Hurricane Bud is expected to move north-northwest on Tuesday into the midweek.
Forecasters said Bud was expected to strengthen further before a slow weakening trend starts Tuesday.
Some 3 to 6 inches of rain accumulations are expected in much of southwestern Mexico, with isolated maximum amounts of 10 inches, the NHC said in the advisory. Bud is the second official hurricane to develop in a week in the eastern Pacific Ocean. "These rains could cause life-threatening flash floods and mudslides", the agency warned.
"Swells generated by Bud will continue to affect portions of the coast of southwestern Mexico during the next few days", the NHC said. The storm peaked on Friday as a Category 4 hurricane with winds of 140 miles per hour (220 kph).