Monday December 2, 2002

MONTHLY CLIMATE SUMMARY - WESTERN AUSTRALIAN REGIONAL OFFICE

Perth dazzled by record sunshine hours in November

Mean daily sunshine hours a new record: The mean daily sunshine hours in Perth in November this year was 11.9 hours compared with the long-term average of 10.4 hours. This was the highest mean daily sunshine hours in November in 105 years of records. The previous high was 11.8 hours in 1999.

Rainfall: Perth received 25.8 millimetres of rain over three days in November compared with the average of 22mm over six days. The heaviest daily fall was 22.8mm on 1 November, which was the wettest November day since 25.2mm fell on 14 November 1992. Historically, November rainfall has ranged from a low of 0.0mm in 1891 to 73.2mm in 1984. Total rainfall for the 11-month period ending 30 November, the year to date, is 734.0mm. This is below the average (to the end of November) of 855mm. The total for the same period last year was 683.8mm.

Maximum temperatures: Perth's mean daily maximum temperature for November of 26.6 degrees Celsius was above the average of 25 degrees. Daily maxima ranged from a cool 17.7 degrees on the 1st - the lowest November maximum temperature since 16.0 degrees was recorded on 8 November 1992 - to 37.9 degrees on 14 November, the highest November maximum temperature since 37.8 degrees was recorded on 24 November 1993. It was also the highest maximum temperature for the year to date.

Minimum temperatures: Perth's mean daily minimum temperature in November was 13.7 degrees, close to the average of 13 degrees. The lowest minimum was a cool 7.5 degrees on the 3rd. A warm 21.4 degrees on the 15th was the highest.

November averages
Element Nov.
2002		 Average Highest
average		 Year Lowest
average		 Year Years of
record
Maximum temp (°C) 26.6 25 27.7 1920 21.5 1971 106
Minimum temp (°C) 13.7 13 16.9 1982 11.9 1954 106
Sunshine (hours/day) 11.9 10.4 11.9 2002 5.1 1965 105
November rainfall averages and extremes
Element Nov.
2002		 Average Highest Year Lowest Year Years of
record
Rainfall (mm) 25.8 22 73.2 1984 0.0 1891 127
Rain days 3 6 14 1939,50,65 0 1891 127

November daily extremes
Element Nov. 2002 Date Extreme Date Years of
record
Highest daily maximum (°C) 37.9 14th 40.3 24/11/1913 106
Lowest daily maximum (°C) 17.7 1st 14.2 19/11/1992 106
Lowest daily minimum (°C) 7.5 3rd 5.6 1/11/1904 106
Highest daily minimum (°C) 21.4 15th 25.1 24/11/1920 106
Wettest 24-hour period (mm) 22.8 1st 39.1 29/11/1956 123

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 monthly averages
Element Average Highest
average		 Year Lowest
average		 Year Years of
record
Maximum temp (°C) 28 31.7 1931 24.3 1922 105
Minimum temp (°C) 15 19.6 1977 14.0 1952 105
Sunshine (hours/day) 11.8 12.4 1975 8.0 1925 104
December rainfall and rain days
Element Average Highest Year Lowest Year Years of
record
Rainfall (mm) 14 80.7 1951 0.0 * many 126
Rain days 4 14 1913,44 0 * many 126

* Denotes Nil rainfall totals recorded in the following Decembers: 1886, 1924, 1949, 1994 and 1997.

December daily extremes
Element Highest Date Lowest Date Years of
record
Max temperature (deg.C) 42.3 31/12/1968 14.9 17/12/1952 105
Min temperature (deg.C) 27.1 18/12/1979 8.6 29/12/1957 105
Rainfall (mm) 24 hours to 9am 46.7 03/12/1951 - - 105

Very hot days: Perth can expect a maximum temperature of 40 degrees or higher in December in one in four years. The highest number of such December days was two, in 1968, 1974, 1977 and 1997. The last time Perth recorded a very hot day in December was on 26 December 1997 with 40.5 degrees, the hottest Boxing Day on record.

Hot days: On average, Perth can expect about six days in December when the maximum temperature is 32 degrees or higher. The highest number of such December days was 18 in 1931, Perth's warmest December on record with a mean maximum temperature of 31.7 degrees. Last December, Perth recorded no such hot days for the first time in 104 years of records.

December's top 10 hottest days December's top 10 coolest days
Position Date Max temp
(deg.C)		 Position Date Max temp
(deg.C)
1 31 December, 1968 42.3 1 17 December 1952 14.9
2 20 December, 1904 42.2 2 15 December 1961 17.6
3 25 December, 1968 42.0 3 31 December 1959 17.8
3 20 December, 1974 42.0 3 01 December 1935 17.9
5 23 December, 1997 41.4 5 30 December 1904 18.3
6 27 December, 1976 41.2 6 02 December 1954 18.4
6 18 December, 1987 41.2 7 14 December 1955 18.5
8 17 December, 1993 41.0 8 06 December 1922 18.8
9 11 December, 1927 40.9 8 02 December 1952 18.8
9 31 December, 1939 40.9 10 01 December 1910 18.9
9 16 December, 1991 40.9 10 01 December 1952 18.9
9 30 December, 1994 40.9 - - -

Note: Official Perth observations have been recorded at several different sites over the years. Changes in site location can affect both temperature and rainfall readings. Due to a relatively short period of record for the current site, temperature averages have been estimated to represent that site.

Ends

Further information:
John Relf (JR), or Glenn Cook, tel:(08) 9263 2222 or, after hours, the senior forecaster.