Perth in May 2010

Cool nights in May for Perth

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.
  • Near average rainfall.
  • Near average maximum temperature.
  • Below average minimum temperature.

Rainfall

Rainfall around the Perth metropolitan area in May 2010 was mainly near average, apart from the offshore and coastal locations of Rottnest and Swanbourne which received above average rainfall for the month. A cold front crossed the Perth region overnight on the 12th, producing the first significant rainfall for May 2010, while stronger fronts associated with low pressure systems to the south of Perth caused rainfall during latter parts of the month. Monthly totals were generally in the 80 to 100 mm range.

Perth Metro recorded 88.6 mm of rainfall on 7 days in May, compared with the average of 117.7 mm on about 12 days. May 2010 was Perth's wettest May since 2005 when Perth Metro last exceeded it's May average with 191.2 mm on 16 days. Historically, May rainfall in Perth Metro has ranged from 14.1 mm in 1964 to 308.1 mm in 1879. Last May, Perth Metro registered 46.0 mm of rainfall on 4 days.

Maximum temperature

Daily maximum temperatures in the Perth area during May 2010 were near average, apart from Rottnest which was cooler than average. A warm day was experienced on the 7th, with Pearce RAAF reaching 30.4 °C while other sites in the Perth area observed maximum temperatures in the high 20's. A much cooler day was experienced around the Perth area on the 13th with Bickley recording the coolest daytime temperature for the month of 12.9 °C as a cold front crossed the Lower West district

Perth Metro's mean daily maximum temperature in May 2010 was 21.7 °C, which is near the average of 22.4 °C. This was Perth Metro's coolest May since 2007. Last year, Perth Metro experienced its warmest May on record with 24.4 °C. Daily maxima ranged from a warm 27.5° C on the 7th to a cool 16.7 °C on the 13th. Perth Metro's coldest day in May on record was 11.5 °C on 23rd May 1995.

Minimum temperature

Overnight minimum temperatures were below average across the Perth area in May 2010. Jandakot Aerodrome and Gosnells City both broke their lowest May daily minimum temperature records on the 15th, while Jandakot Aerodrome and Swanbourne experienced their coldest May on record in terms of average daily minimum temperature.

Perth Metro's mean minimum temperature in May was 8.9 °C, which is below the average of 10.7 °C, and was Perth Metro's coolest May since 2006. Daily minima ranged from a mild 14.9 °C on the 22nd to a cold 2.5 °C on the 15th, which was Perth Metro's coldest May night for six years. Perth Metro's coldest May night on record was 1.3 °C on 11th May 1914.

Wind & sunshine

Severe winds were recorded at Rottnest Island on the 22nd (91 km/h) and the 27th (96 km/h) as cold fronts crossed the Perth area.

Perth recorded a daily average of 7.4 hours of sunshine, which is above the long term average of 6.8 hours.

Further information

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Extremes in May 2010
Hottest day 30.4 °C at Pearce RAAF on the 7th
Warmest days on average 22.6 °C at Gosnells City
Coolest days on average 19.2 °C at Bickley
Coldest day 12.9 °C at Bickley on the 13th
Coldest night -0.1 °C at Jandakot Aero on the 15th
Coolest nights on average 6.8 °C at Jandakot Aero
Warmest nights on average 14.4 °C at Rottnest Island
Warmest night 17.8 °C at Rottnest Island on the 21st
Wettest overall 117.4 mm at Bickley
Wettest day 36.4 mm at Bickley on the 23rd
Highest wind gust 96 km/h at Rottnest Island on the 27th



Record lowest May temperature
Lowest temperature
in May 2010 (°C)
Previous lowest
for May
Years of
record
Average for
May
Jandakot Aero -0.1 on the 15th 0.4 on the 25th in 2006 20 9.5
Gosnells City 4.0 on the 15th 4.1 on the 27th in 2004 18 12.1



Record lowest May mean daily minimum temperature
Mean daily minimum
temperature
for May 2010 (°C)
Previous lowest
for May
Years of
record
Average for
May
Jandakot Aero 6.8 7.0 in 2006 19 9.5
Gosnells City 9.8 10.8 in 2000 17 12.1
Swanbourne 11.1 11.4 in 1995 16 12.7

Lowest May mean daily minimum temperature for at least 10 years
Mean daily minimum
temperature
for May 2010 (°C)
Most recent May
this low or lower
Years since
lower
Average for
May
Pearce RAAF 8.0 7.9 in 1968 42 10.9
Perth Airport 8.3 6.9 in 1968 42 10.5
Medina Research Centre 8.7 8.1 in 1987 19 10.5
Rottnest Island 14.4 14.0 in 1995 15 15.3



Summary statistics for May 2010
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2010
Diff
from
average
Highest for
May
2010
Mean for
May
2010
Diff
from
average
Lowest for
May
2010
Total for
May
2010
Average
for
May
Rank of
May
2010
Fraction of
May
average
Bickley 19.2 -0.2 26.5 7th 9.4 -0.9 5.5 14th 117.4 130.9 average 90%
Champion Lakes 21.4   28.8 7th 10.9   5.2 15th 74.2
Garden Island HSF 20.2   23.1 11th 12.7   8.9 8th 63.2
Gosnells City 22.6 -0.2 29.0 7th 9.8 -2.3 4.0 15th 93.3 105.5 average 88%
Jandakot Aero 21.9 -0.1 28.5 7th 6.8 -2.7 -0.1 15th 91.0 108.3 average 84%
Medina Research Centre 21.9 -0.1 28.0 20th 8.7 -1.8 2.1 15th 89.8 98.1 average 92%
Pearce RAAF 22.5 +0.6 30.4 7th 8.0 -2.9 0.9 15th 61.4 86.4 low 71%
Perth Airport 22.3 +0.6 29.5 7th 8.3 -2.2 1.1 15th 86.0 100.7 average 85%
Perth Metro* 21.7 -0.7 27.5 7th 8.9 -1.8 2.5 15th 88.6 117.7 average 75%
Rottnest Island 20.0 -1.2 23.2 8th 14.4 -0.9 9.5 27th 81.8 70.0 high 117%
Swanbourne 21.6 -0.6 27.9 20th 11.1 -1.6 6.3 15th 106.2 89.2 high 119%

Daily rainfall
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley 2.6 - - - - - - - - - - - 25.2 1.6 - - - - - - - 21.2 36.4 0.2 - - 26.4 3.6 - 0.2 -
Champion Lakes 1.4 0.2 - - - - - - - - - - 9.6 - - - - - - - - 26.6 19.2 - - - 14.6 2.4 0.2 - -
Garden Island HSF 1.6 - - 0.2 - - - - - - - - 6.2 0.2 - - - - - - - 27.0 12.6 0.2 - - 10.0 5.0 0.2 - -
Gosnells City 1.3 - - - - - - - - - - - 19.7 - - - - - - - - 18.4 22.8 0.4 - - 23.6 7.1 - - -
Jandakot Aero 1.6 - - - - - - - 0.2 - - - 8.0 0.2 - - - - - - - 29.8 16.4 0.4 - - 23.4 11.0 - - -
Jarrahdale 2.8 0.2 - 0.2 0.2 0.2 0.2 0.2 0.2 - 0.2 0.2 8.4 0.4 0.4 - - 0.2 0.2 0.2 - 24.2 17.8 - 0.2 0.2 32.4 4.4 0.4 0.2 -
Medina Research Centre 2.0 - - - - - - - - - - - 8.4 0.6 - - - - - - - 26.2 20.0 0.4 - - 22.6 9.6


Mundaring 3.6 0.2 0.2




0.2 0.2

11.0 2.0 0.2
0.2
0.2 0.2
23.2 30.8 0.2 0.2 0.2 34.0 7.4 0.2 0.2 0.2
Pearce RAAF


- - - - - - - - - 13.0 0.4 - - - - - - - 17.4 9.4 - - - 14.8 6.2 0.2 - -
Perth Airport 0.6 0.2 - - - - - - - - - - 19.6 - 0.2 - - - - - - 18.6 18.2 0.2 - - 16.6 11.8 - - -
Perth Metro 2.4 0.2 - - - - - - - - - - 20.4 - - - - - - - - 20.0 19.0 - - - 16.6 10.0 - - -
Rottnest Island 4.2 - - - - - - - - - - - 13.0 1.2 - - - - - - 0.2 33.2 13.4 - - - 10.4 6.2 - - -
Serpentine 3.6 0.2 - - - - -























Swanbourne 2.4 - - - - - - - - - - - 15.0 - - - - - - 0.2 - 25.0 11.4 - - - 29.0 23.0 0.2 - -

Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with »» are part of a longer accumulation, which is marked like this on the final day. Values over 100 mm have been rounded to the nearest whole millimetre. Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.


Notes

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.

A Monthly Climate Summary is prepared to list the main features of the weather in Perth using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 1 pm on Monday 31 May 2010. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Averages are long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record.
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Records in this summary are based on sites with at least 10 years of data.

*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 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 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.

For PDF files of Perth Metro climate statistics for other months, please click here for extremes and here for averages.

Further information

Media
(03) 9669 4057
Enquiries