5:15am 15/07/2026 to 5:15am 17/07/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
3.2 mm
6:15pm 16/07/2026
6:30pm 16/07/2026
1 in 1 years
100.0 %
30m
5.4 mm
6:15pm 16/07/2026
6:45pm 16/07/2026
1 in 1.0 years
99.72 %
45m
7.0 mm
6:00pm 16/07/2026
6:45pm 16/07/2026
1 in 1.0 years
98.83 %
60m
8.2 mm
6:00pm 16/07/2026
7:00pm 16/07/2026
1 in 1.0 years
98.39 %
90m
11.8 mm
6:00pm 16/07/2026
7:30pm 16/07/2026
1 in 1.1 years
89.97 %
120m
14.0 mm
6:00pm 16/07/2026
8:00pm 16/07/2026
1 in 1.2 years
85.53 %
3h
17.0 mm
4:45pm 16/07/2026
7:45pm 16/07/2026
1 in 1.3 years
79.63 %
4h
22.2 mm
3:30pm 16/07/2026
8:00pm 16/07/2026
1 in 1.5 years
66.24 %
6h
24.6 mm
2:00pm 16/07/2026
8:00pm 16/07/2026
1 in 1.5 years
65.97 %
9h
30.8 mm
11:00am 16/07/2026
8:00pm 16/07/2026
1 in 1.8 years
56.22 %
12h
32.8 mm
10:45am 16/07/2026
10:45pm 16/07/2026
1 in 1.7 years
59.65 %
18h
32.8 mm
10:00am 16/07/2026
4:00am 17/07/2026
1 in 1.4 years
72.34 %
24h
32.8 mm
4:00am 16/07/2026
4:00am 17/07/2026
1 in 1.2 years
81.18 %
30h
32.8 mm
10:00pm 15/07/2026
4:00am 17/07/2026
1 in 1.1 years
87.15 %
36h
32.8 mm
4:00pm 15/07/2026
4:00am 17/07/2026
1 in 1.1 years
89.78 %
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.

