6:45am 14/07/2026 to 6:45am 16/07/2026
Maximum observed rainfall by duration, estimated return period and AEP
Duration
Rainfall
Start
End
Years
AEP
15m
2.0 mm
5:15pm 15/07/2026
5:30pm 15/07/2026
1 in 1 years
100.0 %
30m
3.0 mm
5:00pm 15/07/2026
5:30pm 15/07/2026
1 in 1 years
100.0 %
45m
4.0 mm
5:00pm 15/07/2026
5:45pm 15/07/2026
1 in 1 years
100.0 %
60m
5.0 mm
5:00pm 15/07/2026
6:00pm 15/07/2026
1 in 1 years
100.0 %
90m
7.0 mm
5:00pm 15/07/2026
6:30pm 15/07/2026
1 in 1 years
100.0 %
120m
7.5 mm
4:30pm 15/07/2026
6:30pm 15/07/2026
1 in 1 years
100.0 %
3h
9.5 mm
3:45pm 15/07/2026
6:45pm 15/07/2026
1 in 1 years
100.0 %
4h
10.5 mm
3:15pm 15/07/2026
7:45pm 15/07/2026
1 in 1 years
100.0 %
6h
10.5 mm
1:45pm 15/07/2026
7:45pm 15/07/2026
1 in 1 years
100.0 %
9h
14.5 mm
3:45pm 15/07/2026
12:45am 16/07/2026
1 in 1 years
100.0 %
12h
17.5 mm
3:45pm 15/07/2026
3:45am 16/07/2026
1 in 1 years
100.0 %
18h
19.5 mm
12:00pm 15/07/2026
6:00am 16/07/2026
1 in 1 years
100.0 %
24h
19.5 mm
6:00am 15/07/2026
6:00am 16/07/2026
1 in 1 years
100.0 %
30h
19.5 mm
12:00am 15/07/2026
6:00am 16/07/2026
1 in 1 years
100.0 %
36h
19.5 mm
6:00pm 14/07/2026
6:00am 16/07/2026
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.

