Around half a million people are being evacuated to safer areas in south east Bangladesh, ahead of a cyclone that could be extremely dangerous.
Cyclone Mocha is predicted to make landfall on Sunday, with 170kph winds and storm surges of up to 12 feet.
There are concerns the cyclone could impact the world's largest refugee camp, Cox's Bazar, where close to a million people live in makeshift homes.
Rains are already falling on the camp and red warning flags have been raised.
Cyclone Mocha could be the most powerful cyclone seen in Bangladesh in nearly two decades.
As the weather system heads towards the Bangladesh-Myanmar coast, nearby airports have been shut, fishermen have been told to suspend their work, and 1,500 shelters have been set up, as the process of moving people from vulnerable areas begins.
Officials in Cox's Bazar said 1,000 people had already been evacuated from one area, with plans to move a further 8,000 people from a ward near the beach if the situation worsens.
"We are ready to face any hazards... we don't want to lose a single life," Vibhushan Kanti Das, additional deputy commissioner at Cox's Bazar told the BBC.
Tourists staying in beach side hotels will be safe, so emergency workers will move locals like fishermen and families who live in more vulnerable homes, the official said.
In Sittwe City, the capital of Rakkhine state, the rain started on Friday night. The streets emptied out as people took shelter, with many seeking to find safety in cyclone shelters on high ground.
There are almost no lifejackets to be found, and the remaining stock is being sold at a higher price. Gas stations also closed on Saturday, making it difficult for people to drive out of the city.
Close to a million Rohingyas refugees remain at risk, living in flimsy bamboo shelters with tarpaulin covers. The UN says it's doing what it can to protect these areas.
Bangladesh's government doesn't allow refugees to leave their camps, so many say they're frightened and unsure of what will happen if their shelters are hit by the storm.
Forecasters expect the cyclone to bring a deluge of rain, which can trigger landslides - a serious danger for those who reside in hillside camps, where landslips are a regular phenomenon.