Tropical Storm Fausto was bringing dangerous surf to the Hawaii Islands on Monday night. Image courtesy NOAA

July 28 (UPI) -- Fausto weakened from a hurricane to a tropical storm Monday, according to forecasters, who warned the Hawaiian Islands to expect "significant surf" over the next couple of days.

The storm was located about 415 miles east-northeast of Hilo, Hawaii, and had maximum sustained winds of 70 mph, the National Hurricane Center said in its 5 p.m. HST update.

It was moving west-northwest at a blistering 16 mph, it said.

No coastal watches or warnings were in effect.