Reports from Tonga's capital, Nuku'alofa say strong winds were being felt there and there were power outages in some areas.
Tonga's government has announced a State of Emergency because of Cyclone Harold - the second in a month.
In March the government made a similar declaration to help prevent the introduction of Covid-19 into the kingdom.
Late yesterday, in a statement, Prime Minister Pohiva Tu'i'onetoa said as an emergency was about to happen due to the destructive force winds and sea rises caused by the cyclone, it was necessary to make another declaration.