No coastal watches or warnings were in effect. Iona is expected to strengthen more over the next couple of days before weakening around the middle of the week.
The hurricane has maximum sustained winds of about 75 mph (120 kph). It was moving in a generally westward direction at about 10 mph (17 kph).
Iona is the first named storm of the hurricane season in the central Pacific.
A second weather system has also formed in the central Pacific. Tropical Depression Two-C is located about 1,140 miles (1,840 kilometers) east-southeast of Honolulu. Maximum sustained winds are around 35 mph (55 kph) and expected to strengthen.