Hurricane Hector has maximum sustained winds of 130 miles per hour (215 kph) with stronger gusts possible.
As of 11 a.m., the Category 3 storm was about 220 miles south of Hilo and continues to weaken, with maximum sustained winds of 115 miles an hour, moving west at 16 mph.
Forecasters with the National Weather Service say surf will rise 12 to 15 feet along east shores of the Big Island, and 6 to 10 feet along east shores of Maui.
A Category Four storm on the Saffir Simpson scale is capable of doing widespread major structural and infrastructure damage; it can easily tear off roofing, shatter windows, uproot palm trees and turn them into projectiles that can kill people.
John, which absorbed a tropical storm called Ileana, is already dumping heavy rain on states in western Mexico, the National Water Commission said. "However, very rough surf is expected to impact mostly south- and east-facing coastal areas of the Big Island".
Meteorologists canceled a tropical storm warning in Hawaii as Hector moved south of the Big Island late Wednesday.
"There will also be an increase in surf over the rest of the Hawaiian Islands through Friday".