6:45am 23/07/2026 to 6:45am 25/07/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
3.4 mm
1:15am 25/07/2026
1:30am 25/07/2026
1 in 1.0 years
98.88 %
30m
3.6 mm
3:00pm 24/07/2026
3:30pm 24/07/2026
1 in 1 years
100.0 %
45m
5.0 mm
2:45pm 24/07/2026
3:30pm 24/07/2026
1 in 1 years
100.0 %
60m
6.4 mm
2:45pm 24/07/2026
3:45pm 24/07/2026
1 in 1.0 years
99.82 %
90m
9.2 mm
2:15pm 24/07/2026
3:45pm 24/07/2026
1 in 1.0 years
97.57 %
120m
11.4 mm
1:45pm 24/07/2026
3:45pm 24/07/2026
1 in 1.1 years
95.02 %
3h
15.8 mm
12:45pm 24/07/2026
3:45pm 24/07/2026
1 in 1.2 years
86.47 %
4h
21.6 mm
11:15am 24/07/2026
3:45pm 24/07/2026
1 in 1.4 years
72.81 %
6h
28.6 mm
9:45am 24/07/2026
3:45pm 24/07/2026
1 in 1.7 years
58.54 %
9h
40.4 mm
10:00am 24/07/2026
7:00pm 24/07/2026
1 in 2.2 years
46.38 %
12h
46.6 mm
8:15am 24/07/2026
8:15pm 24/07/2026
1 in 2.1 years
48.28 %
18h
55.6 mm
8:15am 24/07/2026
2:15am 25/07/2026
1 in 1.9 years
51.49 %
24h
57.6 mm
6:45am 24/07/2026
6:45am 25/07/2026
1 in 1.6 years
61.82 %
30h
59.4 mm
7:30pm 23/07/2026
1:30am 25/07/2026
1 in 1.5 years
68.84 %
36h
69.0 mm
10:45am 23/07/2026
10:45pm 24/07/2026
1 in 1.6 years
60.83 %
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.

