Oman's Civil Aviation Authority issued a thunderstorm warning on Sunday night.
Starting on Monday, between 10mm and 30mm of rain will hit the regions of Dhofar, Al Wusta, South Al Sharqiyah, the Hajar Mountains and adjacent areas.
Oman has been bogged down by heavy rainfall following air depression, a statement by the Civil Defence and Ambulance Authority said.
The CAA has advised the public to be cautious during rainfall and thunder showers, and warned people against crossing running wadis.
"The public are advised to avoid low-lying areas and venturing into the sea due to heavy rains expected from morning to evening on Tuesday over Hajar Mountains and the surrounding areas," a CAA statement said.
A rockslide in Muscat, brought on by heavy rain, damaged vehicles and stopped motorway traffic.
No injuries were reported.
Muscat has grown accustomed to bouts of heavy rainfall, and with heavy showers comes the risk of wadis overflowing.
Last month, Oman's Ministry of Education closed schools in the northern governorates due to heavy rain.
Heavy rain causes floods in Oman
