Friday, 28 February 2003

SEASONAL CLIMATE SUMMARY - WESTERN AUSTRALIAN REGIONAL OFFICE

Perth experiences its warmest summer for three years

Mean daily maximum temperature: Perth's mean maximum temperature for the summer months December to February 2002-03 was 30.6 degrees Celsius compared with the average of 30 degrees. This is the highest mean maximum temperature for summer for three years. The mean maximum temperature in 1999-2000 was 30.9 degrees. Last summer was a much milder 29.3 degrees. Daily maxima this summer ranged from a mild 20.3 degrees on 2 December 2002 to a very hot 41.0 degrees on 9 February 2003, the hottest summer day for five years.

'Century Heat Days': This summer, Perth recorded eight days when the maximum temperature exceeded 37.8 degrees Celsius or 100 degrees Fahrenheit. This is equal with the eight days in 2000-01. Last summer, Perth recorded no century heat days. On average, Perth can expect five 'centuries' during summer. The most number of such days was in 1961-62 with 16 days.

Mean daily minimum temperature: Perth's mean minium temperature for summer was 17.5 degrees compared with the average of 16 degrees. This was the highest mean minimum temperature for summer for three years. The mean minimum temperature in 1999-00 was 18.2 degrees. Last summer was a much cooler 16.3 degrees. The lowest daily minimum this summer was a cool 8.4 degrees on 2 December 2002, the lowest minimum for December on record. The previous record was 8.6 degrees on 29 December 1957. The highest minimum temperature of 25.0 degrees occurred on 23-24 December 2002.

Summer mean daily sunshine hours: Perth's mean daily sunshine hours for summer was 11.4 hours, which is close to the long term-average of 11.5 hours.

Rainfall: Summer rainfall in Perth this summer was below average. Perth received 16.2 millimetres over 12 days compared with the average of 36.0mm over 10 days. Last summer, Perth recorded 31.4mm over 10 days. Historically, summer rainfall has ranged from a low of 0.8mm in 1974-75 to 180.4mm in 1954-55. Rainfall totals for individual summer months were: December 3.8mm (av 14mm), January 1.4mm (av 9mm), and February 11.0mm (av 13mm). The wettest day was 2 February when 9.8mm of rain fell.

Summer rainfall totals (mm) since 1990-91
Year Rainfall (mm) Rain days Departure from
the average (mm)
1990-91 35.2 7 -1
1991-92 166.2 14 +130
1992-93 31.2 8 -5
1993-94 4.2 6 -32
1994-95 12.0 3 -24
1995-96 6.2 5 -30
1996-97 24.8 11 -11
1997-98 1.8 2 -34
1998-99 60.8 9 +25
1999-00 146.2 13 +110
2000-01 9.8 8 -26
2001-02 31.4 10 -5
2002-03 16.2 12 -20

Seasonal averages - summer
Element Summer
2002-03		 Average Highest
average		 Season Lowest
average		 Season Years of
record
Maximum temp (°C) 30.6 30 32.0 1977-78 26.4 1901-02 106
Minimum temp (°C) 17.5 16 20.3 1977-78 15.4 1901-02 106
Sunshine (hours/day) 11.4 11.5 12.2 1997-98 8.4 1922-23 105
Seasonal rainfall averages and extremes - summer
Element Summer
2002-03		 Average Highest Season Lowest Season Years of
record
Rainfall (mm) 16.2 36 180.4 1954-55 0.8 1974-75 127
Rain days 12 10 20 1913-14 2 *Twice 127

*Least number of rain days of summer occurring in 1902,03 and 1974,75.

Seasonal daily extremes - summer
Element Summer
2002-03		 Date Extreme Date Years of
record
Highest daily maximum (°C) 41.0 09/02/2003 46.2 23/02/1991 106
Lowest daily minimum (°C) 20.3 02/12/2002 14.9 17/12/1952 106
Lowest daily minimum (°C) 8.4 02/12/2002 8.4 02/12/2002 106
Highest daily minimum (°C) 25.0 23,24/12/2002 29.3 †Several 106
Wettest 24-hour period 9.8 02/02/2003 120.6 09/02/1992 123

† Highest summer minimum temperature on record have occurred on the following dates: February 6, 1898, February 8, 1933 and February 3, 1962.

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.