Dark mode
Light mode 5:15am 16/07/2026 to 5:15am 18/07/2026
You can find out more about Design Rainfall and IFD here.
Observations for this analysis :
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
2.8 mm
5:00am 17/07/2026
5:15am 17/07/2026
1 in 1 years
100.0 %
30m
3.4 mm
11:00pm 17/07/2026
11:30pm 17/07/2026
1 in 1 years
100.0 %
45m
4.8 mm
11:00pm 17/07/2026
11:45pm 17/07/2026
1 in 1 years
100.0 %
60m
5.8 mm
10:45pm 17/07/2026
11:45pm 17/07/2026
1 in 1 years
100.0 %
90m
6.6 mm
11:00pm 17/07/2026
12:30am 18/07/2026
1 in 1 years
100.0 %
120m
8.2 mm
10:45pm 17/07/2026
12:45am 18/07/2026
1 in 1.0 years
99.97 %
3h
10.2 mm
9:00pm 17/07/2026
12:00am 18/07/2026
1 in 1.0 years
99.8 %
4h
12.8 mm
8:15pm 17/07/2026
12:45am 18/07/2026
1 in 1.0 years
99.22 %
6h
15.0 mm
8:30pm 17/07/2026
2:30am 18/07/2026
1 in 1.0 years
98.67 %
9h
20.2 mm
4:00pm 17/07/2026
1:00am 18/07/2026
1 in 1.0 years
95.7 %
12h
23.6 mm
4:00pm 17/07/2026
4:00am 18/07/2026
1 in 1.1 years
92.94 %
18h
30.4 mm
8:45am 17/07/2026
2:45am 18/07/2026
1 in 1.2 years
85.74 %
24h
35.6 mm
2:30am 17/07/2026
2:30am 18/07/2026
1 in 1.3 years
77.66 %
30h
38.0 mm
10:00pm 16/07/2026
4:00am 18/07/2026
1 in 1.3 years
77.12 %
36h
38.0 mm
4:00pm 16/07/2026
4:00am 18/07/2026
1 in 1.2 years
81.91 %
Note: A '1 in 1.0 years' estimate means that it is almost certain to occur at least once in a year, and could occur much more than once per year on average. For smaller values like this the Annual Recurrance Interval (ARI) may be of more relevance, but it is complex to calculate for common events.
IFD describes how rainfall intensity relates to how long it lasts and how often it happens. It is the basis for design rainfall used in engineering and flood studies.
- Duration: the length of the rainfall burst, from a few minutes to several days.
- AEP (Annual Exceedance Probability): the chance, in any one year, of a rainfall of that depth or greater. A 1% AEP event has a 1 in 100 chance each year - what is often loosely called a '1 in 100 year' event.
- The curves show design rainfall depths for a range of AEPs. The observed maximums for this location and period are plotted against them so you can see how rare the event was.
Design rainfall data is sourced from the Bureau of Meteorology.
Install
