Tuesday,2 June 2009 - Monthly Climate Summary for Perth - Product Code: IDCKGC11LO

Perth experiences its warmest May on record

Mean daily maximum temperature - highest on record: Perth's mean daily maximum temperature in May was 24.4°C, compared with the average of 22.3°C. This was the highest mean daily maximum temperature for May for Perth since records commenced 1897. The previous highest was 24.0°C in May 2003.  Daily maxima in May 2009 ranged from a cool 16.1°C on the 23rd to a warm 28.5°C on the 5th.

Perth's top 10 mean maximum temperatures
for May
Year
Mean Maximum Temperatures (°C)
Departure from normal
Ranking
2009
24.4
+2.1
1
2003
24.0
+1.7
2
1972
23.9
+1.6
3
1998
23.7
+1.4
4
2005
23.3
+1.0
5
1996
23.1
+0.8
6
1962
23.0
+0.7
7
1976
23.0
+0.7
7
1934
22.9
+0.6
9
2002
22.9
+0.6
9

January to May mean daily maximum temperature - second highest on record:
Perth's mean daily maximum temperature for the January to May period was 29.1°C, compared with the average of 27.8°C. This was the second highest mean daily maximum temperature for this period since records commenced in 1897; the highest being 29.4°C in 1978.

Perth's top 10 mean maximum temperatures
for year to date (January-May)
Year
Mean Maximum Temperatures (°C)
Departure from normal
Ranking
1978
29.4
+1.6
1
2009
29.1
+1.3
2
1972
28.5
+0.7
3
1962
28.4
+0.6
4
1976
28.4
+0.6
4
1988
28.4
+0.6
4
1996
28.4
+0.6
4
1985
28.3
+0.5
8
1998
28.3
+0.5
8
2008
28.3
+0.5
8

Mean daily minimum temperature - below average: Perth's mean daily minimum temperature in May was 9.5°C, compared with the average of 10.8°C.  Daily minima ranged from a cold 3.3°C on the 25th to a mild 16.2°C on the 21st. 

Rainfall - very much below average: The city received 46.0 mm of rainfall on 4 days in May compared with the average of 118 mm on about 12 days. The wettest day was the 23rd when 21.0 mm was recorded. This was Perth's driest May since the 31.0 mm on 9 days in 2006.  Historically, May rainfall has ranged from 14.1 mm in 1964, to 308.1 mm in 1879. Last May Perth registered 59.6 mm on 13 days.

Rain days - record low: Perth recorded its least number of rain days for May on record with only 4 days compared with the average of about 12 days. The previous record was 5 rain days in May 1913.

Dry start to May: Perth experienced its driest start to May on record with no rainfall recorded for the first 20 days of the month. The previous driest start was in May 1926 and 1994 with 15 days.

Year to date rainfall - second driest on recordThe total rainfall for January to May this year was 66.2 mm recorded on 16 rain days, making it the second driest start to a year since the 64.3 mm in 1972. The average for January to May is 204 mm whilst last year Perth recorded 275.0 mm in the same period.

Perth's top ten driest Jan-May period
Year
Rainfall (mm)
Rain days
Ranking
1972
64.3
20
1
2009
66.2
16
2
1903
86.0
34
3
1912
86.4
20
4
1983
86.8
28
5
1914
88.9
31
6
1996
90.0
24
7
1959
93.8
33
8
1964
94.9
23
9
1913
97.3
23
10

Mean daily sunshine hours - highest on record: Perth's mean daily sunshine hours in May was 8.1 hours per day, compared with the average of 6.7 hours per day. This was the highest mean daily sunshine hours for Perth for May since sunshine records commenced in 1898. The previous record was 7.9 hours in 2000.

May monthly mean temperature and sunshine
Element

2009

Long- term Average

Highest

Year

Lowest

Year Records Commence
Maximum
Temperature (°C)
24.4
22.3
24.0
2003
18.7
1931/1956
1897
Minimum Temperature (°C)
9.5
10.8
13.8
1972/2005
8.8
2000
1897
Sunshine
(hours per day)
8.1
6.7
7.9
2000
3.4
1905
1898
May rainfall and rain days
Element 2009 Long-term Average Highest Year Lowest Year Records Commence
Rainfall (mm)
46.0
118
308.1
1879
14.1
1964
1876
Rain days
4
12.2
25
1921
5
1913
187

May daily extremes
Element 2009 Date Extreme Date

Records Commence

Highest daily maximum (°C)
28.5
05/05/2009
34.3
01/05/2002
1897
Lowest daily maximum (°C)
16.1
23/05/2009
11.5
23/05/1995
1897
Highest daily minimum (°C)
16.2
21/05/2009
20.8
01/05/1983
1897
Lowest daily minimum (°C)
3.3
25/05/2009
1.3
11/05/1914
1897
Wettest 24 hours to 9am (mm)
21.0
23/05/2009
76.2
17/05/1942
1876

Climate of Perth in June
June is Perth's wettest month of the year, on average. Cool and cloudy days are common. Some are cold, windy and showery, while others are sunny with light winds.

June monthly mean temperatures and sunshine
Element Average Highest Year Lowest Year

Records
Commence

Maximum temperature (°C)
19.3
20.6
1983
15.9
1898
1897
Minimum temperature (°C)
8.6
12.8
1964
5.8
2006
1897

Sunshine (hours per day)

5.9
7.4
2006
2.9
1945
1898
June monthly rainfall and rain days
Element
Average
Highest
Year
Lowest
Year
Records Commence
Rainfall (mm)
177
476.1
1945
24.6
2006
1876
Rain days
15.4
27
1918/1970
5
2006
1876

June daily extremes
Element
Highest
Date
Lowest
Date
Records Commence
Maximum temperature (°C)
28.1
05/06/1975
8.8
26/06/1956
1897
Minimum temperature (°C)
18.7
12/06/1988
−0.7
17/06/2006
1897
Rainfall 24 hours to 9am (mm)
99.1
10/06/1920
n/a
n/a
1876

Warm days in June: On average, Perth can expect 12 days when the maximum temperature is 20°C or more. The greatest number of such days in June was 21 days in 1983. Last June, Perth recorded 17 such days.

Cold days in June: On average, Perth can expect one day when the maximum temperature is 15°C or less. The greatest number of such days in June was 10 in 1931 and 1955. Last June, Perth recorded one such day.

Cold nights in June: Perth has a mean of six cold nights in June when the minimum temperature is 5°C or lower. The greatest number of such nights was 13 in 2006. Last June, Perth recorded 11 such nights.

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 Perth (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 Perth (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) and Glenn Cook
Western Australia Climate Services Centre
on, tel: (08) 9263 2222, office hours.