About 12 millimetres of rain was recorded in Mount Isa since 9am on Saturday until Sunday afternoon. Temperatures also plummeted from 36 degrees on Friday to a cool 20 degrees yesterday.

A huge downpour at Birdsville on Friday forced the Birdsville races to be cancelled. The town received 33mm of rainfall in the 24 hours from 9am on Friday.

Bedourie was heaviest hit, with 57mm falling on the town since 9am on Friday, including 44mm from 9am on Saturday.

Bureau of Meteorology Mount Isa field office manager Michael Glasson said the unseasonal conditions were due to an unexpected low trough that moved through western Queensland during the weekend.

"The monthly average for Mount Isa is 7mm, and [yesterday's] reading of 20 degrees is well below the September average of 31 degrees," he said.

"The cooler weather has come because of a trough system linked to a low pressure system that has mainly come across Victoria and southern New South Wales."

He said the weather should return to normal in coming days.

"Mount Isa should expect some patchy rain [Monday], and it should be cleared up by Tuesday," he said.

"Temperatures are headed for the mid 20s [today], the low 30s on Tuesday, and the mid 30s by Wednesday and Thursday."