6:30pm 13/08/2026 to 6:30pm 15/08/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
10m
4.0 mm
2:30pm 15/08/2026
2:40pm 15/08/2026
1 in 1 years
100.0 %
20m
6.2 mm
2:20pm 15/08/2026
2:40pm 15/08/2026
1 in 1 years
100.0 %
30m
7.4 mm
1:10pm 15/08/2026
1:40pm 15/08/2026
1 in 1 years
100.0 %
60m
10.0 mm
1:10pm 15/08/2026
2:10pm 15/08/2026
1 in 1 years
100.0 %
90m
16.4 mm
1:10pm 15/08/2026
2:40pm 15/08/2026
1 in 1.0 years
99.87 %
120m
17.8 mm
1:00pm 15/08/2026
3:00pm 15/08/2026
1 in 1.0 years
99.87 %
3h
23.0 mm
1:10pm 15/08/2026
4:10pm 15/08/2026
1 in 1.0 years
99.34 %
4h
26.4 mm
11:00am 15/08/2026
3:30pm 15/08/2026
1 in 1.0 years
99.22 %
6h
31.6 mm
10:20am 15/08/2026
4:20pm 15/08/2026
1 in 1.0 years
98.66 %
9h
31.8 mm
8:50am 15/08/2026
5:50pm 15/08/2026
1 in 1.0 years
99.43 %
12h
31.8 mm
5:50am 15/08/2026
5:50pm 15/08/2026
1 in 1.0 years
99.82 %
18h
31.8 mm
11:50pm 14/08/2026
5:50pm 15/08/2026
1 in 1 years
100.0 %
24h
31.8 mm
5:50pm 14/08/2026
5:50pm 15/08/2026
1 in 1 years
100.0 %
30h
31.8 mm
11:50am 14/08/2026
5:50pm 15/08/2026
1 in 1 years
100.0 %
36h
31.8 mm
5:50am 14/08/2026
5:50pm 15/08/2026
1 in 1 years
100.0 %
48h
31.8 mm
6:30pm 13/08/2026
6:30pm 15/08/2026
1 in 1 years
100.0 %
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.

