Perth Monthly Climate Summary: July 2006
Driest year to date on record for Perth

Tuesday 1 August, 2006

Seven-monthly rainfall - record low: The total rainfall for January to July this year was 215.6 mm, making it the driest such period on record. The previous record was 304.5 mm in 1940. The average is 555 mm.

Perth's top 10 driest years to date
(January to July total)
Season
Rainfall (mm)
Rain Days
Ranking
2006
215.6
46
1
1940
304.5
53
2
1977
307.4
46
3
1894
340.0
53
4
1914
345.5
64
5
2004
353.0
51
6
1979
362.8
62
7
1949
364.4
64
8
1972
365.0
57
9
1993
366.0
51
10

July Rainfall - well below average: The city received 81.0 mm of rainfall over 13 days in July compared with the average of 171 mm over 17 days. This was Perth's sixth driest July on record, the driest being 61.5 mm in 1876. The wettest day in July 2006 was the 25th when 19.4 mm was recorded. Last July Perth registered 62.8 mm on 14 days, the second driest July on record for Perth.

June and July rainfall - record low: The total rainfall for June and July this year was 105.6 mm, making it the driest June and July period for Perth on record. The previous record was 166.2 mm in 1977. The average is 350 mm.

Mean daily maximum temperature - near average: Perth's mean daily maximum temperature in July was 18.8°C, compared with the average of 18.3°C. Daily maxima ranged from a cool 14.6°C on the 21st to a warm 23.0°C on the 8th.

Mean daily minimum temperature - below average: Perth's mean daily minimum temperature in July was 6.5°C, compared with the average of 8.0°C. This was the lowest mean daily minimum temperature for July since the 6.0 degrees in 2001. Daily minima ranged from a very cold 0.2°C on the 22nd to a mild 13.6°C on the 9th.

July monthly mean temperature and sunshine
Element

2006

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
18.8
18.3
19.9
1976/77
15.7
1910
1897
Minimum
Temperature (°C)
6.5
8.0
11.4
1921
5.3
1997
1897
Sunshine
(hours per day)
7.0
6.1
7.5
1918
3.2
1926
1898
July rainfall and rain days
Element 2006 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
81.0
171
425.1
1958
61.5
1876
1876
Rain days
13
17
29
1946
6
1918
1876

July daily extremes
Element 2006 Date Extreme Date

Records Commence

Highest daily maximum (°C)
23.0
08/07/2006
26.3
*Twice
1897
Lowest daily maximum (°C)
14.6
21/07/2006
10.5
09/07/1906
1897
Highest daily minimum (°C)
13.6
09/07/2006
16.1
12/07/1898
1897
Lowest daily minimum (°C)
0.2
22/07/2006
0.0
**Twice
1897
Wettest 24 hours to 9am (mm)
19.4
25/07/2006
95.0
29/07/1987
1876

*Denotes the highest maximum temperature for July on record on the following dates: 17 & 18 July 1976.
**Denotes the lowest minimum temperature for July on record on the following dates: 15 July 1997 and 27 July 1998.

Climate of Perth in August

August heralds the end of winter and generally shows signs of the forthcoming change in the season. Mean temperatures are generally similar to those in July, but there is a slight reduction in the mean rainfall. Mean sunshine hours increase, with an extra 1.0 hours per day on average.

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

Records
Commence

Maximum temperature
(°C)
18.5
20.3
1902
16.3
1932
1897
Minimum temperature
(°C)
8.1
11.5
1977/83
6.9
1956/2001
1897

Sunshine
(hours per day)

7.1
8.4
1902
4.2
1945
1898
August rainfall and rain days
Element
Average
Highest
Year
Lowest
Year
Records Commence
Rainfall (mm)
135
318.3
1945
11.8
1902
1876
Rain days
16
29
1955
4
1902/78
1876

August daily extremes
Element
Highest
Date
Lowest
Date
Records Commence
Maximum temperature (°C)
27.8
21/08/1940
9.9
05/08/1951
1897
Minimum temperature (°C)
16.6
13/08/1976
1.3
21/08/2000
1897
Rainfall 24 hours to 9am (mm)
73.9
14/08/1945
n/a
n/a
1876

Warm days in August: On average, Perth can expect a warm day one year in five, when the maximum temperature is 25 degrees or higher. The greatest number of warm days in August was 4 in 1914. There were none in August last year.

Cold days in August: On average, Perth can expect one day when the maximum temperature is 15 degrees or less. The greatest number of such days was 10 in 1917. There were two such days in August last year.

Cold nights in August: On Average, Perth can expect seven nights when the minimum temperature is 5 degrees or less. The greatest number of such nights was 11 in 1999 and 2001, and there were four in August last year.

August top 10 warmest days
August top 10 coldest days
Position
Date
Max
Temp°C
Position
Date
Max
Temp°C
1
21 August 1940
27.8
1
05 August 1951
9.9
2
12 August 1914
27.2
2
06 August 1900
10.4
2
11 August 1948
27.2
3
27 August 1968
10.8
2
26 August 1949
27.2
4
11 August 1931
10.9
2
26 August 1998
27.2
5
07 August 1920
11.2
6
20 August 1940
27.1
6
09 August 1917
11.3
7
24 August 1914
27.0
7
07 August 1932
11.5
8
30 August 1902
26.9
8
01 August 1909
11.7
8
12 August 1976
26.9
8
02 August 1932
11.7
10 22 August 1978 26.8 8 25 August 1932 11.7
- - - 8 01 August 1945 11.7

August top 10 warmest nights
August top 10 coldest nights
Position
Date
Min
Temp°C
Position
Date
Min
Temp°C
1
13 August 1976
16.6
1
21 August 2000
1.3
2
17 August 1999
16.1
2
11 August 1997
1.4
3
12 August 1987
16.0
2
04 August 2000
1.4
4
04 August 1947
15.9
2
13 August 2002
1.4
5
03 August 1964
15.8
2
19 August 2005
1.4
5
27 August 1998
15.8
6
22 August 2000
1.5
7
08 August 1977
15.7
6
15 August 2004
1.5
8
13 August 1910
15.6
8
31 August 1908
1.8
8
10 August 1915
15.6
8
18 August 2001
1.8
10 26 August 1985 15.4 10 17 August 2001 2.1

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 John Cramb Western Australia Climate Services Centre
on, tel: (08) 9263 2222, office hours.