Indonesian authorities are turning to the technique of cloud seeding to try to stop more rain falling in the flood-hit capital Jakarta.
Planes have been sent to inject chemicals into clouds in an effort to alter precipitation.
Jakarta and surrounding districts have struggled to cope since a storm on New Year's Eve left large areas underwater.
At least 43 people are known to have died, with some 192,000 evacuated. More rain is expected.
According to Reuters news agency, two planes have been sent up to shoot salt flares into the clouds, with the aim of making them break before they reach the Jakarta region.
"All clouds moving towards the Greater Jakarta area, which are estimated to lead to precipitation there, will be shot with NaCl (sodium chloride) material," Indonesia's technology agency BPPT explained in a statement.
The Indonesian disaster management agency said it was using inflatable boats to rescue stranded families. A dozen people remain missing.
By Friday morning, the clean-up operation was under way. On Thursday, authorities had used hundreds of pumps to try to lower water levels in residential areas and around public infrastructure, like the railways.
But even in areas where the water has receded, mud and debris are preventing many residents from returning home.
Floods are common in the city around this time of year, and are among the reasons President Joko Widodo plans to move the capital to East Borneo in the next few years.
Mr Widodo blamed the severity of current disaster on delays in flood control infrastructure projects.
It is the worst flooding in the area since 2013.
Jakarta, home to millions of people, is one of the fastest-sinking cities in the world. Experts say it could be entirely submerged by 2050.