2:45pm 08/08/2026 to 2:45pm 10/08/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
5.0 mm
1:45am 10/08/2026
2:00am 10/08/2026
1 in 1.0 years
98.13 %
30m
8.2 mm
1:30am 10/08/2026
2:00am 10/08/2026
1 in 1.1 years
93.27 %
45m
9.8 mm
1:15am 10/08/2026
2:00am 10/08/2026
1 in 1.1 years
92.48 %
60m
11.4 mm
1:00am 10/08/2026
2:00am 10/08/2026
1 in 1.1 years
90.46 %
90m
12.8 mm
1:00am 10/08/2026
2:30am 10/08/2026
1 in 1.1 years
92.35 %
120m
13.8 mm
12:45am 10/08/2026
2:45am 10/08/2026
1 in 1.1 years
93.82 %
3h
16.6 mm
11:00pm 09/08/2026
2:00am 10/08/2026
1 in 1.1 years
92.16 %
4h
21.4 mm
10:15pm 09/08/2026
2:45am 10/08/2026
1 in 1.2 years
85.91 %
6h
23.6 mm
8:45pm 09/08/2026
2:45am 10/08/2026
1 in 1.2 years
86.47 %
9h
25.0 mm
1:00am 10/08/2026
10:00am 10/08/2026
1 in 1.1 years
91.39 %
12h
34.0 mm
1:00am 10/08/2026
1:00pm 10/08/2026
1 in 1.4 years
72.53 %
18h
44.0 mm
7:15pm 09/08/2026
1:15pm 10/08/2026
1 in 1.7 years
59.46 %
24h
47.0 mm
1:00pm 09/08/2026
1:00pm 10/08/2026
1 in 1.6 years
62.38 %
30h
52.8 mm
7:15am 09/08/2026
1:15pm 10/08/2026
1 in 1.8 years
56.03 %
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.

