Hurricane Eric, the larger of the storms, is not expected to make landfall, but parts of Hawaii may experience increased gusts of wind and rain as Eric slides south of the Big Island Thursday.
It is expected to weaken by a tropical storm by then, said CNN meteorologist Haley Brink.
"Strong swellings are expected to cause a dangerous surf along the east and south coasts of Hawaii over the next 48-72 hours, but no coastal councils are currently being issued for the Hawaii Islands chain," Brink said.
sustained winds stood at 130 mph, officials say.
Hurricane Eric is the fifth storm to make its way to the Eastern Pacific so far this season.
The Category 1 storm had maximum sustained winds of 80 mph.
Forecasts bring Flossie to the Category 2 storm by Friday, but are not expected to affect Hawaii until next week.
With the strengthening of the two storms, the National Oceanic and Atmospheric Administration (NOAA) says it will monitor them via satellite.
Eric is due to leave Hawaiian waters by Saturday.