Tuesday, 1 December 2009 - Monthly Climate Summary for Perth - Product Code: IDCKGC11LO

Above average rainfall for November in Perth

November Rainfall - above average The city received 38.2 mm of rainfall over 4 days in November, compared with the average of 22 mm on about 6 days. This was the first time Perth has exceeded its average monthly rainfall, for any month, since November 2008. The wettest day in November was 22.4 mm on the 19th, which was the wettest November day for 7 years, since the 22.8 mm on the 1st November 2002. Historically, November rainfall has ranged from nil in 1891 to 73.2 mm in 1984. Last November Perth recorded 57.8 mm on 13 days.

Year to date rainfall - very much below average: The total rainfall for the 11-month period, January-November 2009, was 608.2 mm on 108 days, which was the driest January to November since 2006, then 461.6 mm. The average for the January to November period is 841 mm on about 108 days. The total rainfall for the same period last year was 796.2 mm on 110 days

Mean daily maximum temperature - near average: Perth's mean daily maximum temperature in November was 26.5°C, compared with the average of 26.2°C. Daily maxima ranged from a mild 20.2°C on the 19th to a hot 35.8°C on the 24th. Last November Perth recorded it's coldest November since 1991 with a mean daily maximum temperature of 23.6°C.

January to November mean daily maximum temperature - equal second highest on record: Perth's mean daily maximum temperature for the January to November period was 24.5°C, which was the equal second highest mean daily maximum temperature on record, along with 1988. The average for the January to November period is 24.0°C. The highest mean daily maximum temperature recorded for January to November in Perth was 24.8°C in 1978.

Perth's top 6 mean maximum temperatures
for year to date (January-November)
Year
Mean Maximum Temperatures (°C)
Departure from normal
Ranking
1978
24.8
+0.8
1
1988
24.5
+0.5
2
2009
24.5
+0.5
2
1972
24.4
+0.4
4
1976
24.4
+0.4
4
1985
24.4
+0.4
4

Mean daily minimum temperature - near average: Perth's mean daily minimum temperature in November was 13.8°C, compared with the average of 14.1°C. Daily minima ranged from a cool 8.6°C on the 27th, to a warm 20.2°C on the 12th.

November monthly mean temperature and sunshine
Element

2009

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
26.5
26.2
28.5
2007
21.5
1971
1897
Minimum
Temperature (°C)
13.8
14.1
16.9
1982
11.9
1954
1897
Sunshine
(hours per day)
10.4
10.7
12.3
2007
5.1
1965
1898
November rainfall and rain days
Element 2009 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
38.2
22
73.2
1984
0.0
1891
1876
Rain days
4
6.4
14
3 years
0
1891
1876

November daily extremes
Element 2009 Date Extreme Date

Records Commence

Highest daily maximum (°C)
35.8
24/11/2009
40.3
*Several
1897
Lowest daily maximum (°C)
20.2
19/11/2009
15.8
02/11/1919
1897
Highest daily minimum (°C)
20.2
12/11/2009
25.1
24/11/1920
1897
Lowest daily minimum (°C)
8.6
27/11/2009
5.0
18/11/2004
1897
Wettest 24 hours to 9am (mm)
22.4
19/11/2009
39.1
29/11/1956
1876

* Denotes the highest daily maximum temperature recorded on 24 November 1913 and 11 November 2003.

Climate of Perth in December

December is typically a dry month and days are generally sunny and warm to hot. On most afternoons a sea breeze moderates the temperature. December is Perth's sunniest month on average with 11.6 hours of sunshine per day.

December mean temperatures and sunshine
Element Average Highest Year Lowest Year

Records
Commence

Maximum temperature
(°C)
28.7
31.7
1931
23.7
2005
1897
Minimum temperature
(°C)
16.1
19.6
1977
13.9
2005
1897

Sunshine
(hours per day)

11.6
12.6
2000
8.0
1925
1898
December rainfall and rain days
Element
Average
Highest
Year
Lowest
Year
Records Commence
Rainfall (mm)
13
80.7
1951
0.0
5 years
1876
Rain days
4.1
14
1913/44
0
5 years
1876

December daily extremes
Element
Highest
Date
Lowest
Date
Records Commence
Maximum temperature (°C)
44.2
26/12/2007
14.9
17/12/1952
1897
Minimum temperature (°C)
27.1
18/12/1979
7.9
07/12/2007
1897
Rainfall 24 hours to 9am (mm)
46.7
03/12/1951
n/a
n/a
1876

Very hot days: Perth can expect one day in December when the maximum temperature is 40°C or higher. The highest number of such December days was two in 1968, 1974, 1977, 1997, 2002 and 2007. The last time Perth recorded a very hot day in December was on 26 December 2007 with 44.2°C.

Hot days: On average, Perth can expect seven days in December when the maximum temperature is 32°C or higher. The highest number of hot days in December was eighteen in 1931, Perth's warmest December on record with a mean maximum temperature of 31.7°C. Last December, Perth recorded 5 hot days.

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), or Yanhui Blockley tel: (08) 9263 2222 on weekdays.