Weather

Perth 28-day rainfall forecast

Sun Mon Tue Wed Thu Fri Sat
28
 
 
29
 
 
30
Low
 
31
Low
 
1
Med
Jun
2
Med
 
3
Med
 
4
 
 
5
 
 
6
 
 
7
 
 
8
 
 
9
 
 
10
 
 
11
 
 
12
Low
 
13
Low
 
14
 
 
15
Med
 
16
Med
 
17
Low
 
18
Low
 
19
Low
 
20
Low
 
21
Low
 
22
 
 
23
 
 
24
Low
 

Chance of rainfall somewhere within district

Nil
<25%
Low
25-50%
Medium
50-75%
High
≥75%

Issue Notes

Issued 27 May 2017

The hemispheric long wave pattern has remained stable in recent weeks. There are five main troughs. Currently the most significant troughs are near the longitudes of South Africa, the Indian Ocean, eastern Australia, the southeast Pacific, and the Atlantic Ocean. Summary: Over southern and eastern Australia the cold front events with potential to bring widespread rain are now expected about 30 May to 3 June, 17 June to 21 June, and 25 June to 29 June. Rain events originating in the tropics and moving south are possible about 12 June to 16 June, 18 June to 22 June, and 22 June to 26 June. Over Western Australia the strongest cold fronts should occur about 8 June to 12 June, 24 June to 28 June, and 28 June to 2 July.

Forecast Explanation

This forecast is produced by a multi-model ensemble consisting of dynamical atmospheric models, which are forced by the latest observed atmosphere, ocean, land and ice conditions. The models are designed to simulate features of the real atmosphere, including the daily movement of long and short wave patterns in the Southern Hemisphere.

The future probability of rain in each district is estimated using output from the multi-model ensemble, combined with historical information about the difference between the model forecasts and observed rainfall.

In this deterministic framework the skill of the forecast tends to decrease with time, however the forecasts are updated daily to provide the latest estimates of rainfall probability out to 28 days.