Monday, 3 September 2007 - Monthly Climate Summary for Perth - Product Code:IDCKGC11L0

An average August in Perth

Rainfall - near average: The city received 130.8 mm of rainfall over 20 days in August compared with the average of 135 mm on about 16 days. Historically, August rainfall has ranged from 11.8 mm in 1902 to 318.3 mm in 1945. The wettest day in August 2007 was the 11th when 23.6 mm was recorded.

Year to date rainfall - below average: The total rainfall for January to August this year was 536.8 mm recorded on 83 days compared with the average of 687 mm on about 77 days. Last year Perth recorded its driest January to August period on record with 340.4 mm.

Mean daily maximum temperature - near average: Perth's mean daily maximum temperature in August was 19.0°C, compared with the average of 18.7°C. Daily maxima ranged from a cold 14.5°C on the 10th, the lowest daily maximum temperature for August since the 13.3°C on 28 August 2004, to a warm 24.3°C on the 18th.

Mean daily minimum temperature - near average: Perth's mean daily minimum temperature in August was 8.8°C, compared with the average of 8.2°C. Daily minima ranged from a cold 3.1°C on the 12th and 13th to a mild 14.5°C on the 23rd.

August monthly mean temperature and sunshine
Element

2007

Long- term Average

Highest

Year

Lowest

YearRecords Commence
Maximum
Temperature (°C)
19.0
18.7
20.3
1902
16.3
1932
1897
Minimum Temperature (°C)
8.8
8.2
11.5
1977/1983
6.9
1956/2001
1897
Sunshine
(hours per day) #
6.4
7.1
8.4
1902
4.2
1945
1898
August rainfall and rain days
Element2007Long-term AverageHighestYearLowestYearRecords Commence
Rainfall (mm)
130.8
135
318.3
1945
11.8
1902
1876
Rain days
20
16.2
29
1955
4
1902/1978
1876

August daily extremes
Element2007DateExtremeDate

Records Commence

Highest daily maximum (°C)
24.3
18/08/2007
27.8
21/08/1940
1897
Lowest daily maximum (°C)
14.5
10/08/2007
9.9
05/08/1951
1897
Highest daily minimum (°C)
14.5
23/08/2007
17.0
07/08/2006
1897
Lowest daily minimum (°C)
3.1
12 &13/08/2008
1.3
21/08/2000
1897
Wettest 24 hours to 9am (mm)
23.6
11/08/2007
73.9
14/08/1945
1876

Climate of Perth in September
September is the first month of spring. The warming and drying trends accelerate in Perth as monthly rainfall and the number of wet days typically fall, whilst mean maximum and minimum temperatures and the number of sunshine hours increase, heralding the end of winter and showing signs of the change in season.

September monthly mean temperatures and sunshine
ElementAverageHighest YearLowest Year

Records
Commence

Maximum temperature (°C)
20.1
22.6
1987
16.8
1915
1897
Minimum temperature (°C)
9.5
12.4
1988
8.0
2004
1897

Sunshine (hours per day)

7.7
8.8
4 years
4.9
1907
1898
September monthly rainfall and rain days
Element
Average
Highest
Year
Lowest
Year
Records Commence
Rainfall (mm)
81
199.1
1923
8.7
1916
1876
Rain days
15.2
26
1915
4
1877
1876

September daily extremes
Element
Highest
Date
Lowest
Date
Records Commence
Maximum temperature (°C)
32.7
30/09/1918
11.4
17/09/1917
1897
Minimum temperature (°C)
19.5
08/09/1916
1.5
* Twice
1897
Rainfall 24 hours to 9am (mm)
51.8
14/09/1984
n/a
n/a
1876

* Denotes the lowest minimum temperature for September on record on the following dates: 1 and 10 September 2005.

Warm days in September: On average, Perth can expect two days when the maximum temperature is 25°C or higher. The record is 10 days in 1987, when the highest mean daily maximum temperature on record for September of 22.6°C was recorded.

Earliest 32-degree day of the season (hot day): The earliest 32-degree maximum temperature of the season was on 18 September 1988, when 32.3°C was recorded, the second highest temperature for September on record.

Cold days in September: On average, Perth can expect approximately one day every five years when the maximum temperature is 15°C or lower. The record is four days in 1903 and there were no such days in 2006.

Cold nights in September: On average, Perth can expect three nights when the minimum is 5°C or lower. The record is seven nights in 2004 and there were four such nights in 2006.

Note: Official Perth observations have been recorded at several different sites with varying instrumentation over the years, and these changes can affect the continuity of the climate record. For the current Perth (Mount Lawley) site, the most significant changes of this kind relate to temperature and rain days. For that reason, current mean temperature and rain-day data quoted here are based only on readings from the Perth (Mount Lawley) site, which commenced observations in 1993. Sunshine recordings are from Perth Airport and for similar reasons current means use only Perth Airport data, which commenced in 1993.

Further information:
John Relf (JR) and Glenn Cook Western Australia Climate Services Centre
on, tel: (08) 9263 2222, office hours.