Thursday, 3 January 2008- Monthly Climate Summary for Perth - Product Code:IDCKGC11L0

Wettest December for 11 years in Perth

December rainfall - above average: The city received 18.0 mm of rainfall on 7 days in December, which was the wettest December since 20.6 mm in 1996. The average for December is 13 mm on about four days. Historically, December rainfall has ranged from zero in five Decembers to 80.7 mm in 1951. Last December Perth registered 5.2 mm on two days.

Mean daily maximum temperature - below average: Perth's mean daily maximum temperature in December was 27.7°C, making it the lowest mean daily maximum temperature for December since 23.7°C in 2005. The average for December is 28.8°C. Last December was a warm 30.4°C. Daily maxima ranged from a mild 20.1°C on the 6th to a hot 44.2°C on the 26th (Boxing Day), which was the hottest daily maximum temperature in Perth for December on record. The previous record being 42.3°C on 31 December 1968.

Mean daily minimum temperature - below average: Perth's mean daily minimum temperature in December was 15.2°C, compared with the average of 16.2°C. Last December was 16.4°C. Daily minima ranged from a cool 7.9°C on the 7th, which was the lowest daily minimum temperature for December on record, to a warm 21.4°C on the 27th.

December monthly mean temperature and sunshine
Element

2007

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
27.7
28.8
31.7
1931
23.7
2005
1897
Minimum
Temperature (°C)
15.2
16.2
19.6
1977
13.9
2005
1897
Sunshine
(hours per day)
10.6
11.7
12.6
2000
8.0
1925
1898
December rainfall and rain days
Element 2007 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
18.0
13
80.7
1951
0.0
5 years
1876
Rain days
7
3.6
14
1913/1944
0
5 years
1876

December daily extremes
Element 2007 Date Extreme Date

Records Commence

Highest daily maximum (°C)
44.2
26/12/2007
42.3
31/12/1968
1897
Lowest daily maximum (°C)
20.1
06/12/2007
14.9
17/12/1952
1897
Highest daily minimum (°C)
21.4
27/12/2007
27.1
18/12/1979
1897
Lowest daily minimum (°C)
7.9
07/12/2007
8.4
02/12/2002
1897
Wettest 24 hours to 9am (mm)
5.8
18/12/2007
46.7
09/12/1951
1876

Climate of Perth in January

It is midsummer in Perth in January, and days are generally sunny and either warm or hot. The low humidity that generally occurs on days of high temperature makes conditions more tolerable. Sea-breezes that blow across the coastal plain on most afternoons moderate the temperature. Hot spells, usually of two or three days, duration, are commonly followed by milder conditions. On average, January is Perth's driest month with 10 mm of rain on about two days.

January mean temperatures and sunshine
Element Average Highest Year Lowest Year

Records
Commence

Maximum temperature
(°C)
30.3
34.4
1962
26.3
1939
1897
Minimum temperature
(°C)
17.6
20.9
1978
15.6
3 years
1897

Sunshine
(hours per day)

11.6
12.6
1974
8.3
1920
1898
January and rain days
Element
Average
Highest
Year
Lowest
Year
Records Commence
Rainfall (mm)
10
139.0
2000
0.0
12 years
1876
Rain days
2.4
8
1916/1990
0
12 years
1876

January daily extremes
Element
Highest
Date
Lowest
Date
Records Commence
Maximum temperature (°C)
45.8
31/01/1991
19.7
* Twice
1897
Minimum temperature (°C)
27.8
21/01/1989
8.9
25/01/2001
1897
Rainfall 24 hours to 9am (mm)
104.0
22/01/2000
n/a
n/a
1876

Denotes lowest January maximum temperature on record has occurred on the following dates: 19 January 1939 and 3 January 2007.

Very hot days in January: On average, Perth can expect one day when the maximum temperature is 40°C degrees or higher. The greatest number of such days in January was four in 1961, 1965 and 1968. The last time Perth recorded such a day in January was on 28 January 2007 when 41.6°C was recorded.

Hot days in January: On average, Perth can expect eleven days when the maximum temperature is 32°C or higher. The highest number of such days in January was 24 in 1962, when the record highest mean maximum temperature for January (34.4°C) was set.

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