The weather in Mount Isa in September is hot. The average temperatures are between 18°C and 31°C. Usually the days in September are hot while the nights are a bit cooler.
You can expect a few rainy days in Mount Isa during September, but usually the weather is comfortable in September.
Our weather forecast can give you a great sense of what weather to expect in Mount Isa in September 2025.
If you’re planning to visit Mount Isa in the near future, we highly recommend that you review the 14 day weather forecast for Mount Isa before you arrive.
Temperatures
31° / 18°
Rainy Days
1
Snowy Days
0
Dry Days
29
Rainfall
24
mm
Sun Hours
11.0
Hrs
