Monday, 2 April 2001

MONTHLY CLIMATE SUMMARY - WESTERN AUSTRALIAN REGIONAL OFFICE

March a month of contrasts in WA

Rainfall and rain days - well below average: Perth received 2.8 millimetres of rain on two days in March compared with the long-term average of 19mm over four days. This was the driest March since 1991, which also measured 2.8mm. Historically, March rainfall has ranged from a low of 0.0mm in many years to 145.2mm in 1934. The wettest day this month was 15 March when 2.2mm was recorded. The total for the three months ending 31 March was 12.2mm, the lowest since 5.6mm in 1994. The long-term average is 41 mm.

Mean daily maximum temperature - about average: Perth's mean maximum temperature in March was 29.3 degrees Celsius compared with the long-term average of about 29 degrees. The beginning of the month from the 1st to the 6th was Perth's hottest start to March on record; the mean maximum temperature for this period was 38.0 degrees. Daily maxima for the month ranged from a mild 21.4 degrees on 16 March to a very hot 39.7 on the 3rd - the highest March maximum temperature since 40.5 degrees was recorded on 9 March 1996.

Mean daily minimum temperature - below average: Perth's mean daily minimum temperature in March was 15.3 degrees compared with the long-term average of about 16 degrees. The lowest daily minimum was a cold 7.6 degrees on the 24th - the lowest March minimum temperature on record. The previous record of 7.7 degrees occurred on 25 March 1899 and 8 March 1903. This month's highest daily minimum of 25.1 degrees occurred on the 4th.

Mean daily sunshine hours - new record: Perth's mean daily sunshine hours this March was 10.6 hours compared with the long-term average 9.3. This March had the highest mean daily sunshine hours in 102 years of records. The previous record was 10.5 in 1955 and 1973.

Climate of Perth in April

Sunny and pleasantly mild days are common in April in the transition between summer and winter. Wet weather does occur, especially later in the month, and mean rainfall and rain days are about double those of March.

April monthly averages and extremes
Elements Average Highest Year Lowest Year
Maximum temperature (°C) 25 28.1 1978-99 21.0 1968
Minimum temperature (°C) 12 17.3 1978 11.5 1914
Relative humidity 0900 (%) 65 76 1961-68 52 1977
Relative humidity 1500 (%) 49 60 1966-66 39 1952-99
Sunshine (hours/day) 8.2 9.3 1920 4.4 1926
April rainfall and rain days
Elements Average Highest Year Lowest Year
Rainfall (mm) 46 148.8 1926 0.0 * A few
Rain days 8 19 1926 0 * A few

* denotes nil rainfall and rain days in 1920,1977 and 1982.

April daily extremes
Element Highest Date Lowest Date
Maximum temperature (°C) 37.6 09/04/1910 13.6 16/04/1919
Minimum temperature (°C) 24.4 02/04/1913 4.1 20/04/1914
Rainfall (mm) 24 hours to 9am 66.5 30/04/1904 - -

Hot days in April: On average, Perth can expect about one day when the maximum temperature is 32 degrees or higher. The greatest number of such hot days in April was eight in 1991.

Latest 35.0-degree day of the season: The latest maximum of 35.0 degrees of the season occurred on 22 April 1989 when 35.2 degrees was recorded.

Cold days in April: Since 1897, Perth has recorded six days in April when the maximum temperature was 15 degrees or lower. They were in 1900, 1919, 1931, 1963, and two days in 1970. The earliest such cold day for the year occurred on 15 April 1900 with 14.5 degrees.

April's top 10 hottest and coolest days
Position Date Max
Temp°C		 Position Date Max
Temp°C
1 9 April 1910 37.6 1 16 April 1919 13.6
2 3 April 1971 37.1 2 23 April 1963 14.0
3 5 April 1906 36.7 3 15 April 1900 14.5
4 10 April 1899 36.3 4 23 April 1931 14.8
5 1 April 1937 36.1 5 21 April 1970 14.9
6 7 April 1897 36.0 6 20 April 1970 15.0
6 2 April 1907 36.0 7 21 April 1980 15.4
6 16 April 1972 36.0 8 29 April 1922 15.9
6 4 April 1978 36.0 9 30 April 1904 16.0
10 13 April 1950 35.9 9 20 April 1926 16.0

Note: Official Perth observations have been recorded at several different sites over the years. Changes in site location can affect both the temperature and the rainfall readings. The long-term temperature averages have been calculated for the current site.

Ends

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