Cyclone Gonu, with winds of 160 miles per hour and gusts of 195 miles per hour, is heading northwest through the Indian Ocean toward Oman's east coast.
Authorities on Monday evacuated nearly 7,000 people from Masirah, a lowland island off the east coast of Oman, said General Malik bin Suleiman al-Muamri, head of the country's civil defense.
He said that a state of emergency was declared in the affected area, including mobilizing army and police forces to help provide shelter and medical services. More families were also leaving their homes in towns on the mainland on Tuesday, officials said. The government said schools and public building were emptied to make room for the evacuees.
By Tuesday afternoon, the pan-Arab satellite Al-Jazeera television station reported that the storm had reached the equivalent of a category five hurricane and was expected to make landfall within hours.
Authorities also took precautionary emergency measures in major oil installations which remained operating Tuesday. Most of the nation's key oil facilities are on the northeastern coast of Oman and not directly in the storm's projected path.
Oil prices edged upward, though the cyclone was not necessarily the reason, said Tom Kloza, chief oil analyst at the Oil Price Information Service. Oman's oil reserves and production are small compared to some of its Middle Eastern neighbors.
The government in neighboring Saudi Arabia issued a statement reassuring its people and the oil markets that it would not be seriously affected by the storm.
Many areas have already been hit heavy rain and strong wind.
The most powerful part of the storm was expected to hit Oman on Thursday, before moving north into southern Iran.
Gonu is expected to be the strongest cyclone to hit the Arabian Peninsula since record keeping started in 1945. A cyclone is the term used for hurricanes in the Indian Ocean and Western Pacific.