5:30pm 08/08/2026 to 5:30pm 10/08/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
7.0 mm
8:30am 10/08/2026
8:45am 10/08/2026
1 in 1.0 years
98.32 %
30m
10.4 mm
8:30am 10/08/2026
9:00am 10/08/2026
1 in 1.0 years
95.31 %
45m
11.8 mm
8:15am 10/08/2026
9:00am 10/08/2026
1 in 1.0 years
96.28 %
60m
12.4 mm
8:15am 10/08/2026
9:15am 10/08/2026
1 in 1.0 years
98.25 %
90m
13.0 mm
8:00am 10/08/2026
9:30am 10/08/2026
1 in 1.0 years
99.29 %
120m
15.0 mm
11:00am 10/08/2026
1:00pm 10/08/2026
1 in 1.0 years
98.93 %
3h
21.4 mm
6:30am 10/08/2026
9:30am 10/08/2026
1 in 1.1 years
93.09 %
4h
27.6 mm
8:30am 10/08/2026
1:00pm 10/08/2026
1 in 1.2 years
85.43 %
6h
31.4 mm
6:30am 10/08/2026
12:30pm 10/08/2026
1 in 1.2 years
81.57 %
9h
42.4 mm
6:30am 10/08/2026
3:30pm 10/08/2026
1 in 1.6 years
62.81 %
12h
44.8 mm
4:00am 10/08/2026
4:00pm 10/08/2026
1 in 1.5 years
67.43 %
18h
44.8 mm
8:00pm 09/08/2026
2:00pm 10/08/2026
1 in 1.2 years
83.62 %
24h
50.6 mm
4:00pm 09/08/2026
4:00pm 10/08/2026
1 in 1.3 years
79.76 %
30h
50.6 mm
10:00am 09/08/2026
4:00pm 10/08/2026
1 in 1.1 years
88.01 %
36h
50.8 mm
4:00am 09/08/2026
4:00pm 10/08/2026
1 in 1.1 years
91.78 %
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.

