9:00pm 17/08/2026 to 9:00pm 19/08/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
2.4 mm
4:15pm 19/08/2026
4:30pm 19/08/2026
1 in 1 years
100.0 %
30m
4.6 mm
5:45pm 19/08/2026
6:15pm 19/08/2026
1 in 1 years
100.0 %
45m
6.6 mm
5:45pm 19/08/2026
6:30pm 19/08/2026
1 in 1.0 years
99.87 %
60m
8.0 mm
3:45pm 19/08/2026
4:45pm 19/08/2026
1 in 1.0 years
99.79 %
90m
11.4 mm
3:15pm 19/08/2026
4:45pm 19/08/2026
1 in 1.0 years
98.47 %
120m
14.4 mm
4:15pm 19/08/2026
6:15pm 19/08/2026
1 in 1.0 years
96.77 %
3h
21.6 mm
3:30pm 19/08/2026
6:30pm 19/08/2026
1 in 1.2 years
85.78 %
4h
30.6 mm
2:30pm 19/08/2026
7:00pm 19/08/2026
1 in 1.4 years
69.34 %
6h
36.2 mm
2:00pm 19/08/2026
8:00pm 19/08/2026
1 in 1.5 years
67.44 %
9h
41.8 mm
11:45am 19/08/2026
8:45pm 19/08/2026
1 in 1.3 years
74.12 %
12h
49.8 mm
8:45am 19/08/2026
8:45pm 19/08/2026
1 in 1.5 years
68.5 %
18h
51.0 mm
2:45am 19/08/2026
8:45pm 19/08/2026
1 in 1.2 years
84.58 %
24h
52.2 mm
8:45pm 18/08/2026
8:45pm 19/08/2026
1 in 1.1 years
89.83 %
30h
48.0 mm
1:45pm 18/08/2026
7:45pm 19/08/2026
1 in 1.0 years
96.91 %
36h
53.6 mm
8:45am 18/08/2026
8:45pm 19/08/2026
1 in 1.1 years
95.02 %
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.

