Dark mode
Light mode 9:40pm 22/08/2026 to 9:40pm 24/08/2026
You can find out more about Design Rainfall and IFD here.
Observations for this analysis :
Maximum observed rainfall by duration, estimated return period and AEP
Incomplete record: 2 of the 268 intervals in this period were not measured. A duration is only listed where every interval within it was observed, so some durations may be missing and the totals below cover the observed intervals only.
Duration
Rainfall
Start
End
Years
AEP
10m
0.8 mm
9:50pm 23/08/2026
10:00pm 23/08/2026
1 in 1 years
100.0 %
20m
0.8 mm
9:40pm 23/08/2026
10:00pm 23/08/2026
1 in 1 years
100.0 %
30m
0.8 mm
9:30pm 23/08/2026
10:00pm 23/08/2026
1 in 1 years
100.0 %
60m
0.8 mm
9:00pm 23/08/2026
10:00pm 23/08/2026
1 in 1 years
100.0 %
90m
0.8 mm
8:30pm 23/08/2026
10:00pm 23/08/2026
1 in 1 years
100.0 %
120m
0.8 mm
8:00pm 23/08/2026
10:00pm 23/08/2026
1 in 1 years
100.0 %
3h
1.0 mm
9:10pm 23/08/2026
12:10am 24/08/2026
1 in 1 years
100.0 %
4h
1.2 mm
9:50pm 23/08/2026
2:20am 24/08/2026
1 in 1 years
100.0 %
6h
1.2 mm
8:20pm 23/08/2026
2:20am 24/08/2026
1 in 1 years
100.0 %
9h
1.2 mm
5:20pm 23/08/2026
2:20am 24/08/2026
1 in 1 years
100.0 %
12h
1.4 mm
7:00pm 23/08/2026
7:00am 24/08/2026
1 in 1 years
100.0 %
18h
1.6 mm
8:20am 23/08/2026
2:20am 24/08/2026
1 in 1 years
100.0 %
24h
1.8 mm
7:00am 23/08/2026
7:00am 24/08/2026
1 in 1 years
100.0 %
30h
1.8 mm
1:00am 23/08/2026
7:00am 24/08/2026
1 in 1 years
100.0 %
36h
1.8 mm
9:40pm 22/08/2026
9:40am 24/08/2026
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.
Install
