Wednesday 1 August, 2007 - Monthly Climate Summary for Perth - Product Code: IDCKGC11L0

Third warmest July on record for Perth

Mean daily maximum temperature - above average: Perth's mean daily maximum temperature in July was 19.5°C, compared with the average of 18.3°C. This was the third highest mean maximum temperature recorded for July in Perth, the highest mean maximum temperature for July being 19.9°C in both 1976 and 1977. Daily maxima ranged from a cool 16.9°C on the 24th to a warm 23.8°C on the 7th, which was the highest daily maximum temperature for July since the 24.5°C on 17 July 2002.

Mean daily minimum temperature - very much above average: Perth's mean daily minimum temperature in July was 10.0°C, compared with the average of 7.9°C. This was the highest mean minimum temperature for July since the 10.3°C in 2000. Daily minima ranged from a cold 3.4°C on the 15th to a mild 14.3°C on the 2nd.

Cold nights: Perth recorded four cold nights this July with a minimum temperature of 5°C or less. The average for July is eight nights. Last July Perth recorded eight cold nights whilst the greatest number of such nights in July was 16 in 1998 and 2001.

Rainfall - average: The city received 179.4 mm of rainfall over 19 days in July compared with the average of 170 mm on about 17 days. July 2007 has been the wettest July since the 182.6 mm in 2001. Historically, July rainfall has ranged from 61.5 mm in 1876, to 425.1 mm in 1958. The wettest day in July 2007 was the 2nd when 27.8 mm was recorded.

Year to date rainfall - below average: The total rainfall for January to July this year was 406.0 mm recorded on 63 days compared with the average of 552 mm over 61 days. Last year Perth recorded its driest January to July period on record with 215.6 mm

July monthly mean temperature and sunshine
Element

2007

Long- term Average

Highest

Year

Lowest

YearRecords Commence
Maximum
Temperature (°C)
19.5
18.3
19.9
1976/1977
15.7
1910
1897
Minimum Temperature (°C)
10.0
7.9
11.4
1921
5.3
1997
1897
Sunshine
(hours per day)
5.3
6.1
7.5
1918
3.2
1926
1898
July rainfall and rain days
Element2007Long-term AverageHighestYearLowestYearRecords Commence
Rainfall (mm)
179.4
170
425.1
1958
61.5
1876
1876
Rain days
19
17.2
29
1946
6
1918
1876

 

July daily extremes
Element2007DateExtremeDate

Records Commence

Highest daily maximum (°C)
23.8
07/07/2007
26.3
Twice
1897
Lowest daily maximum (°C)
16.9
24/07/2007
10.5
09/07/1906
1897
Highest daily minimum (°C)
14.3
02/07/2007
16.1
12/07/1898
1897
Lowest daily minimum (°C)
3.4
15/07/2007
0.0
†† Twice
1897
Wettest 24 hours to 9am (mm)
27.8
02/07/2007
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
ElementAverageHighest YearLowest Year

Records
Commence

Maximum temperature (°C)
18.7
20.3
1902
16.3
1932
1897
Minimum temperature (°C)
8.2
11.5
1977/1983
6.9
1956/2001
1897

Sunshine (hours per day)

7.1
8.4
1902
4.2
1945
1898
August monthly rainfall and rain days
Element
Average
Highest
Year
Lowest
Year
Records Commence
Rainfall (mm)
135
318.3
1945
11.8
1902
1876
Rain days
16.2
29
1955
4
1902/1978
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)
17.0
07/08/2006
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. when the maximum temperature is 25 degrees or higher, one year in five in August. The greatest number of warm days in August was four in 1914, whilst there was one day 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 none 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.

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.