Myanmar and Bangladesh deployed thousands of volunteers and ordered evacuations from low-lying areas on Thursday as the Bay of Bengal's first cyclone of the year approached.
Cyclone Mocha is forecast to make landfall on Sunday along the Bangladesh-Myanmar border, according to India's meteorological office, packing winds of up to 145 kilometres (90 miles) per hour.
The office predicted a storm surge of between 1.5 and two metres (5-6 feet) for the low-lying coastal region, which on the Bangladeshi side is home to sprawling camps hosting hundreds of thousands of Rohingya refugees.
Thar Tin Maung, 60, was moved from his village in Myanmar's Rakhine state to the town of Sittwe in preparation for the storm.
"As it is located at the entrance to the river, our village can't even resist a small storm," he told AFP.
"There will be some people who cannot move out from the village and I am worried about them."
Ahmadul Haque, director of Bangladesh's Cyclone Preparedness Programme, said they had deployed 8,600 volunteers in Cox's Bazar and another 3,400 Rohingya volunteers in the refugee camps.
"Especially, we are alerting the people living on hill-slopes as the cyclone would bring heavy rains, which can trigger landslides," he told AFP.
Bangladesh also banned fishing boats from venturing into the deep sea.
Cyclones - the equivalent of hurricanes in the North Atlantic or typhoons in the Northwest Pacific - are a regular and deadly menace on the coast of the northern Indian Ocean where tens of millions of people live.
Bangladesh was last hit by a super storm in November 2007 when Cyclone Sidr ripped through the country's southwest, killing more than 3,000 people and causing damage worth billions of dollars.
In May 2008 Cyclone Nargis left at least 138,000 dead or missing in Myanmar, in the country's worst natural disaster.