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Light mode 9:40pm 22/08/2026 to 9:40pm 24/08/2026
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
10m
2.6 mm
8:20pm 23/08/2026
8:30pm 23/08/2026
1 in 1.0 years
99.09 %
20m
3.4 mm
8:20pm 23/08/2026
8:40pm 23/08/2026
1 in 1.0 years
99.32 %
30m
4.6 mm
8:20pm 23/08/2026
8:50pm 23/08/2026
1 in 1.0 years
98.72 %
60m
6.2 mm
8:00pm 23/08/2026
9:00pm 23/08/2026
1 in 1.0 years
98.44 %
90m
6.8 mm
8:10pm 23/08/2026
9:40pm 23/08/2026
1 in 1.0 years
98.56 %
120m
8.8 mm
8:20pm 23/08/2026
10:20pm 23/08/2026
1 in 1.0 years
97.16 %
3h
12.0 mm
8:20pm 23/08/2026
11:20pm 23/08/2026
1 in 1.1 years
93.93 %
4h
16.6 mm
7:50pm 23/08/2026
12:20am 24/08/2026
1 in 1.1 years
87.54 %
6h
17.0 mm
7:00pm 23/08/2026
1:00am 24/08/2026
1 in 1.1 years
89.34 %
9h
19.8 mm
6:30pm 23/08/2026
3:30am 24/08/2026
1 in 1.1 years
88.41 %
12h
20.0 mm
5:10pm 23/08/2026
5:10am 24/08/2026
1 in 1.1 years
90.74 %
18h
20.2 mm
11:10am 23/08/2026
5:10am 24/08/2026
1 in 1.1 years
94.04 %
24h
21.8 mm
6:00pm 23/08/2026
6:00pm 24/08/2026
1 in 1.1 years
93.98 %
30h
22.0 mm
12:00pm 23/08/2026
6:00pm 24/08/2026
1 in 1.0 years
95.26 %
36h
22.2 mm
8:30am 23/08/2026
8:30pm 24/08/2026
1 in 1.0 years
95.66 %
48h
22.2 mm
9:40pm 22/08/2026
9:40pm 24/08/2026
1 in 1.0 years
96.46 %
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.
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