Perth Monthly Climate Summary: August and Winter 2006
Perth's driest and equal warmest winter on record

Friday 1 September, 2006

August Rainfall - below average: The city received 124.8 mm of rainfall over 17 days in August compared with the average of 135 mm over 16 days. The wettest day in August 2006 was the 15th when 27.0 mm was recorded. Last August Perth registered 124.6 mm on 12 days.

Winter Rainfall - record low: The city received a record low winter rainfall of 230.4 mm over 35 days in 2006, compared with the average of 485 mm over 50 days. The previous driest winter was 260.0 mm on 40 days in 1940. Last winter, Perth recorded 438.4 mm over 45 days. Rainfall totals for individual months this winter were: June 24.6 mm (average 179 mm), July 81.0 mm (average 171 mm) and August 124.8 mm (average 135 mm). The wettest day in winter was 15 August when 27.0 mm of rain fell.

Perth's top 10 driest winter's
Season
Rainfall (mm)
Rain Days
Ranking
2006
230.4
35
1
1940
260.0
40
2
1881
303.2
39
3
1971
306.7
47
4
1877
307.6
48
5
1979
314.0
45
6
1914
316.7
43
7
1977
333.2
46
8
1894
333.7
50
9
1976
341.8
40
10

August mean daily maximum temperature - well above average: Perth's mean daily maximum temperature in August was 20.2°C making it the second highest mean maximum temperature for August on record. The warmest August was 20.3°C in 1902 with the average for August being 18.5°C. Daily maxima ranged from a cool 16.0°C on the 16th to a warm 26.7°C on the 29th.
Winter mean daily maximum temperature: The mean daily maximum temperature for Perth this winter of 19.7°C was the equal highest mean daily maximum temperature on record, also recorded in 1976 and 1983. The average for winter is 18.6°C. Last winter the mean daily maximum temperature was 18.3°C. Daily values ranged from a cold 14.6 degrees on 21 July to a warm 26.7°C on the 29 August.

August mean daily minimum temperature - above average: Perth's mean daily minimum temperature in August was 9.7°C, compared with the average of 8.1°C. Daily minima ranged from a cold 3.1°C on the 17th to a warm 17.0°C on the 7th, the highest daily minimum temperature on record for August for Perth. The previous record minimum was 16.6°C on 13 August 1976.
Winter mean daily minimum temperature: The mean daily minimum temperature for Perth this winter of 7.4°C was below the average of 8.3°C. This was the second lowest winter mean daily minimum temperature recorded at the official Perth metropolitan observation site at Mt Lawley. Last winter the mean daily minimum temperature was 7.9°C. Daily minima ranged from a cold −0.7°C on 17 June, the lowest temperature ever recorded at the Mt Lawley site, to a warm 17.0°C on 7 August.

Mean daily sunshine hours: Perth's mean daily sunshine hours this winter was 7.1, which was above the long term average of 6.3 hours and the second sunniest winter on record.

August monthly mean temperature and sunshine
Element

2006

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
20.1
18.5
20.3
1902
16.3
1932
1897
Minimum
Temperature (°C)
9.7
8.1
11.5
1977/1983
6.9
1956/2001
1897
Sunshine #
(hours per day)
6.9
7.1
8.4
1902
4.2
1945
1898
August rainfall and rain days
Element 2006 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
124.8
135
318.3
1945
11.8
1902
1876
Rain days
17
16
29
1955
4
1902/1978
1876

# This is a preliminary figure based on the available data at the time of issue of this summary. Please check updated mean sunshine hours from Daily Weather Observations for Perth in early September.

August daily extremes
Element 2006 Date Extreme Date

Records Commence

Highest daily maximum (°C)
26.7
29/08/2006
27.8
21/08/1940
1897
Lowest daily maximum (°C)
16.0
16/08/2006
9.9
05/08/1951
1897
Highest daily minimum (°C)
17.0
07/08/2006
16.6
13/08/1976
1897
Lowest daily minimum (°C)
3.1
17/08/2006
1.3
21/08/2000
1897
Wettest 24 hours to 9am (mm)
27.0
15/08/2006
73.9
14/08/1945
1876
Winter mean temperature and sunshine
Element

Winter 2006

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
19.7
18.6
19.7
1976/1983
16.5
1916/1956
1897
Minimum
Temperature (°C)
7.4
8.3
11.0
1964/1983
6.6
2001
1897
Sunshine
(hours per day)
7.1
6.3
7.2
2001
4.1
1926
1898
Winter rainfall and rain days
Element Winter 2006 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
230.4
485
957.1
1945
260.0
1940
1876
Rain days
35
50
68
1926
35
1902
1876

Winter daily extremes
Element Winter
2006
Date Extreme Date

Records Commence

Highest daily maximum (°C)
26.7
29/08/2006
28.1
05/06/1975
1897
Lowest daily maximum (°C)
14.6
21/07/2006
8.8
26/06/1956
1897
Highest daily minimum (°C)
17.0
07/08/2006
18.7
12/06/1988
1897
Lowest daily minimum (°C)
−0.7
17/06/2006
0.0
*Twice
1897
Wettest 24 hours to 9am (mm)
27.0
15/08/2006
99.1
10/06/1920
1876

* Denotes the lowest all-time minimum temperature on record on the following dates: 15 July 1997 and 27 July 1998

Recent winters in Perth
Season
Mean Maximum(°C)
Mean Minimum(°C)
Total Rainfall (mm)
Rain Days
Mean Sunshine (hours per day)
1994
18.9
8.7
535.0
51
6.3
1995
18.3
8.6
512.4
52
6.1
1996
18.6
9.7
555.8
63
5.6
1997
18.8
7.6
361.6
41
6.9
1998
18.2
8.5
414.8
57
5.7
1999
19.2
8.6
401.6
48
6.7
2000
18.5
9.0
497.2
58
6.0
2001
19.1
6.6
382.2
42
7.2
2002
18.8
8.7
384.8
51
6.3
2003
18.3
7.8
464.4
50
6.1
2004
18.4
8.4
411.4
52
6.3
2005
18.3
7.9
438.4
45
6.2
2006
19.7
7.4
230.4
35
7.1

Climate of Perth in September

September is the first month of spring and in Perth a warm drying trend is often experienced. Monthly rainfall and the number of wet days generally decreases, whilst maximum and minimum temperatures and the number of sunshine hours increases.

September monthly mean temperatures and sunshine
Element Average Highest Year Lowest Year

Records
Commence

Maximum temperature
(°C)
20.0
22.6
1987
16.8
1915
1897
Minimum temperature
(°C)
9.4
12.4
1988
8.0
2004
1897

Sunshine
(hours per day)

7.7
8.8
Many
4.9
1907
1898
September 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
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 Perth's warmest September on record, 1987, when the mean maximum temperature was 22.6°C.

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 whilst there were no such days in 2005.

Cold nights in September: On average, Perth can expect three nights each September when the minimum is 5°C or lower. The record is seven nights in 2004 and there were three such nights in 2005.

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 maximum temperature for September on record.

September top 10 hottest days
September top 10 coldest days
Position
Date
Max temp
(°C)
Position
Date
Max temp
(°C)
1
30 September 1918
32.7
1
17 September 1917
11.4
2
18 September 1988
32.3
2
04 September 1931
11.6
3
22 September 1961
32.2
3
01 September 1931
12.1
4
26 September 1961
31.3
4
16 September 1937
12.5
5
14 September 1987
30.9
5
14 September 1947
12.7
6
28 September 1990
30.7
6
17 September 1915
12.9
6
20 September 1994
30.7
6
19 September 1923
12.9
8
12 September 1939
30.6
6
12 September 1950
12.9
8
21 September 1954
30.6
9
20 September 1904
13.0
8
27 September 1954
30.6
10
12 September 1916
13.1
-
-
-
10
10 September 1925
13.1

September top 10 warmest nights
September top 10 coldest nights
Position
Date
Min temp
(°C)
Position
Date
Min temp
(°C)
1
08 September 1916
19.5
1
01 September 2005
1.5
2
30 September 1918
18.9
1
10 September 2005
1.5
3
02 September 1959
18.3
3
11 September 2004
1.7
4
27 September 1936
17.8
4
23 September 1998
1.8
5
20 September 1930
17.7
5
16 September 2002
2.0
6
29 September 1900
17.6
6
03 September 1994
2.3
7
20 September 1985
17.5
7
06 September 1956
2.6
7
28 September 1985
17.5
8
04 September 1998
2.8
9
30 September 1898
17.4
9
08 September 1952
3.1
10
28 September 1930
17.2
9
05 September 1999
3.1
10
26 September 1936
17.2
-
-
-
10
28 September 1998
17.2
-
-
-

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 Mt 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 Mt 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.