One child dead, flights suspended as cyclone approaches Oman
Another person was also reported missing in the flash floods in Al Amarat in Muscat province, Oman's National Committee for Emergency Management said.
Neighbouring United Arab Emirates said it was on "high alert". The storm, with wind speeds of up to 139 kilometres (86 miles) an hour, was 65 kilometres from Muscat and expected to hit Oman's northern coast between 6.00pm and 10.00pm (1400-1800 GMT).
Some flights to and from Muscat International Airport were suspended "to avoid any risks", the airport tweeted, while the Civil Aviation Authority urged people to avoid low-lying areas and valleys.
Oman declared a two-day national holiday on Sunday and Monday, shuttering schools, "due to the adverse climate conditions", the official Oman News Agency said.
The UAE was also bracing for possible impact, with emergency authorities urging people to avoid beaches and low-lying areas.
"We would like to assure everyone that the concerned authorities are on high alert and prepared to deal with any upcoming tropical situation," the UAE's National Emergency Crisis and Disaster Management Authority said on Saturday.