Monday 1 September 2008 - Monthly Climate Summary for Perth - Product Code:IDCKGC11L0

Sunny days and cold nights in August for Perth

Rainfall - very much below average: The city received 27.8 mm of rainfall over 6 days in August, compared with the average of 135 mm on about 16 days, making it the driest August in 30 years and the fourth driest on record.

Between 4 and 19 August, Perth recorded 16 days without rainfall, which is the longest August dry spell since an 18 day period of no measurable rain occurred between 6 and 23 August 1978.

The table below shows Perth's Top 10 driest August's on record.

Perth's Top 10 driest August's
Year
Rainfall (mm)
Rain days
Ranking
1902
11.8
4
1
1978
18.4
4
2
1881
27.5
11
3
2008
27.8
6
4
1956
40.4
10
5
1925
48.3
9
6
1947
54.7
12
7
1940
57.2
12
8
1914
60.1
10
9
1969
62.1
14
10

Year to date rainfall - near average: The total rainfall for January to August this year was 624.2 mm recorded on 72 days, compared with the average of 686 mm on about 77 days.

Mean daily maximum temperature - above average: Perth's mean daily maximum temperature in August was 19.8°C, compared with the average of 18.7°C. Daily maxima ranged from a mild 16.9°C on the 30th, to a warm 24.2°C on the 17th.

Mean daily minimum temperature - record low: Perth's mean daily minimum temperature in August was 5.6°C, compared with the average of 8.3°C. This was the lowest mean daily minimum temperature recorded at the current Perth Metro site for August. The previous lowest mean daily minimum temperature was 6.9°C in August 2001, while 6.9°C was also recorded in 1956. Daily minima ranged from a cold 1.8°C on the 18th to a mild 11.2°C on the 2nd. August 2008 also experienced the most number of cold nights on record, with 15 nights recording a minimum temperature of 5°C or less. The previous record was 11 nights of 5°C or less in 1999 and 2001.

Mean sunshine hours - record high: Perth's mean sunshine hours in August was 8.5°C, which exceeded its previous highest sunshine hours of 8.4, set in August 1902. The average August sunshine hours is 7.1 hours.

August monthly mean temperature and sunshine
Element

2008

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
19.8
18.7
20.3
1902
16.3
1932
1898
Minimum Temperature (°C)
5.6
8.3
11.5
1977/1983
6.9
1956/2001
1898
Sunshine
(hours per day)
8.5
7.1
8.4
1902
4.2
1945
1898
August rainfall and rain days
Element 2008 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
27.8
135
318.3
1945
11.8
1902
1876
Rain days
6
16.2
29
1955
4
1902/1978
1876

 

August daily extremes
Element 2008 Date Extreme Date

Records Commence

Highest daily maximum (°C)
24.2
17/08/2008
27.8
21/08/1940
1897
Lowest daily maximum (°C)
16.9
30/08/2008
9.9
05/08/1951
1897
Highest daily minimum (°C)
11.2
2/08/2008
17.0
07/08/2006
1897
Lowest daily minimum (°C)
1.8
18/08/2008
1.3
21/08/2000
1897
Wettest 24 hours to 9am (mm)
18.2
2/08/2008
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
Element Average Highest Year Lowest 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
15.1
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 2007.

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 two such nights in 2007.

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:
Yanhui Blockley and Glenn Cook Western Australia Climate Services Centre
on, tel: (08) 9263 2222, office hours.