7:15pm 15/08/2026 to 7:15pm 17/08/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
6.6 mm
10:00am 17/08/2026
10:15am 17/08/2026
1 in 1.0 years
96.64 %
30m
10.4 mm
10:00am 17/08/2026
10:30am 17/08/2026
1 in 1.1 years
87.08 %
45m
11.6 mm
10:00am 17/08/2026
10:45am 17/08/2026
1 in 1.1 years
89.91 %
60m
12.4 mm
10:00am 17/08/2026
11:00am 17/08/2026
1 in 1.1 years
93.16 %
90m
13.0 mm
9:30am 17/08/2026
11:00am 17/08/2026
1 in 1.0 years
97.66 %
120m
13.4 mm
9:45am 17/08/2026
11:45am 17/08/2026
1 in 1.0 years
98.85 %
3h
13.6 mm
8:45am 17/08/2026
11:45am 17/08/2026
1 in 1.0 years
99.88 %
4h
14.2 mm
8:30am 17/08/2026
1:00pm 17/08/2026
1 in 1 years
100.0 %
6h
14.8 mm
9:15am 17/08/2026
3:15pm 17/08/2026
1 in 1 years
100.0 %
9h
14.8 mm
6:15am 17/08/2026
3:15pm 17/08/2026
1 in 1 years
100.0 %
12h
14.8 mm
3:15am 17/08/2026
3:15pm 17/08/2026
1 in 1 years
100.0 %
18h
14.8 mm
9:15pm 16/08/2026
3:15pm 17/08/2026
1 in 1 years
100.0 %
24h
14.8 mm
3:15pm 16/08/2026
3:15pm 17/08/2026
1 in 1 years
100.0 %
30h
14.8 mm
9:15am 16/08/2026
3:15pm 17/08/2026
1 in 1 years
100.0 %
36h
14.8 mm
3:15am 16/08/2026
3:15pm 17/08/2026
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.

