Residents have been evacuated and roads and train lines cut off after 150mm of rain fell on the northwest Queensland town of Dajarra overnight.

Residents have been evacuated from homes in a drought-declared Queensland town after heavy rain caused flooding overnight.

Police say the small town of Dajarra, south of Mount Isa, was isolated after 150 millimetres of rain fell overnight, flooding rivers and creeks and cutting off roads and train lines.

Two train workers were stranded after the train line between Mount Isa and Duchess was cut off by floods. They were rescued about 1am (AEST) on Friday and returned to Mount Isa.

Meanwhile, two Cannington Mine workers remain stranded by floods in the McKinlay area.

The pair, who slept in their truck on Thursday night, have been in regular contact with emergency services and are expected to be rescued on Friday.

Rainfall was widespread. Cloncurry, Mount Isa and Camooweal recorded 30-50mm of rain overnight.

Mount Isa police Superintendent Russell Miller said residents were evacuated from two homes in Dajarra on Thursday night due to flooding and a further six homes were inundated.

He said the main road from Mount Isa to Dajarra was cleared of debris and reopened on Friday morning. A number of roads in Dajarra remain closed.

With 70 per cent of Queensland drought-declared, including most of the state’s northwest, many are grateful for the downpour.

“This rain is very, very welcome,” Supt Miller told AAP.

“It’s not drought-breaking but it definitely helps, and there are predictions that more rain is on the way.”

Supt Miller says rain throughout the northwest over recent weeks had changed the landscape.

“The cows are looking a lot happier,” he said.