Perth in May 2013: Wettest May for eight years

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.
  • Rainfall: above average
  • Maximum temperature: near average
  • Minimum temperature: near average

Rainfall

Rainfall across the Perth metropolitan area during May 2013 was above average with monthly rainfall totals generally ranging between 110 mm and 190 mm. For many sites, it was the wettest May for eight years, since May 2005 when the Perth region last received above average May rainfall.

A cloudband associated with a low pressure system to the southwest of WA moved across the Perth metropolitan area on the 1st and 2nd, producing moderate rainfall at most sites. Rainfall totals from the event were in the 10 to 35 mm range. A strong cold front moved through the Perth region in the morning and early afternoon on the 8th, resulting in thunderstorms with strong winds and a wind gust to 106 km/h at Rottnest Island in the early afternoon, and moderate to heavy rainfall across all sites. A daily rainfall total of 61.6 mm at Rottnest Island in the 24 hours to 9am on the 8th was the highest daily rainfall of the month in the Perth area, and it was Rottnest Island's wettest May day for twenty years, since 65.0 mm was recorded on 18 May 1993. Three more fronts followed in succession during the 8th and 9th bringing further moderate to heavy falls to the Perth area, whilst a southwesterly stream persisted to the 11th as light to moderate falls were reported. The event brought totals of 50 mm to 80 mm to most sites over the four days. A cold front moved through the Perth metropolitan area late on the 16th, bringing showers and thunderstorms, though moderate rainfall was mainly confined to the islands and southwestern suburbs. Mostly light showers persisted in the metropolitan area to the 20th when a cold front and low pressure system moved through the Southwest Land Division (SWLD), bringing light to moderate totals to Perth metropolitan sites. A weak low off the SWLD west coast brought showers to the Perth area on the 26th producing light to moderate rainfall at a number of sites, whilst a weak cold front passed through the southwest of WA overnight on the 27th resulting in further light to moderate rainfall across the Perth metropolitan area. Showers persisted in the region in an unstable airmass before a moderate cold front moved through southwest WA overnight on the 29th and in the morning on the 30th bringing moderate rainfall to most of the Perth area. Rainfall totals for the last week of May were typically in the 15 mm to 30 mm range across Perth.

Perth Metro recorded 138.2 mm on 13 rain days in May 2013. It was the wettest May for eight years, since 191.2 mm was recorded on 16 rain days in 2005, and only Perth Metro's third above average May total rainfall in the past 20 years. The highest daily fall for the month for Perth Metro was 43.6 mm on the 8th, the site's wettest day in almost 17 months, since 43.6 mm also was recorded on 13 December 2011, and the wettest May day in over eight years since 50.4 mm was recorded on 2 May 2005. Historically, total May rainfall has ranged from 14.1 mm in 1964 to 308.0 mm in 1879. Last May (2012), Perth Metro recorded 49.0 mm on 9 rain days.

Maximum temperature

Mean maximum temperatures in May 2013 were near average across the Perth metropolitan area with mean maxima in the high teens in the hills and in the low twenties for the remainder of the metropolitan area.

For much of the Perth area, warm days in May 2013 were confined to the first week of the month, as well as the 26th. The 1st was the warmest day of the month for most sites with daily maxima in the mid-twenties as the result of warm northerly winds ahead of an approaching low to the west. Pearce RAAF recorded a maximum temperature of 27.8 °C on the 1st, the highest temperature recorded in the Perth metropolitan area for May 2013. Swanbourne reported its warmest day of the month on the 5th as a developing high south of the Bight directed warm easterly winds over the Perth area with daily maxima again reaching the mid-twenties. The 7th was notable as Garden Island's warmest day of the month with more mid-twenties maxima across Perth as winds tended northerly ahead of an approaching cold front. Relatively frequent frontal passages that brought the above average rainfall for the month resulted in mostly cool to mild days from the 8th onward. The coolest day of the month was the 30th in the cold pool after the passage of a moderate cold front with maxima in the low-to-mid teens. Bickley recorded the coolest day of May 2013 in the Perth metropolitan area on the 30th with a maximum of 11.9 °C.

Perth Metro's mean daily maximum temperature in May 2013 was 21.7 °C, which is below the average of 22.5 °C. Daily maxima ranged from a warm of 25.7 °C on the 1st to a cool of 14.6 °C on 30th, Perth Metro's first sub-15 °C day in over eight months, since a maximum of 14.9 °C was recorded on 27 September 2012.

Minimum temperature

Mean minimum temperatures in May 2013 were near average across the Perth metropolitan area. Mean minima ranged from near 10 °C on the coastal plain and in the hills, to the low-to-mid teens near the coast and on the islands.

Nights during the first 11 days of May 2013 were mainly cool to mild across the Perth metropolitan area with daily minima generally in the low-to-mid teens. The mildest night for most metropolitan sites was the 1st/2nd with minima on the 2nd typically in the 16 °C to 18 °C range. However, for a few sites, their highest minimum temperature for the month was recorded on the 1st or the 8th. Rottnest Island recorded the highest minimum in the Perth metropolitan area for May 2013 on the 1st with a low of 19.7 °C in warm northerly winds and cloudy conditions ahead of an approaching low to the west. In contrast, overnight temperatures often dipped to single digits from the 12th to the end of the month with mostly cold nights, though cool to mild nights returned briefly from the 26th to 28th. The coldest morning of the month was undoubtedly on the 31st in cold air and clear skies after the passage of a cold front. All metropolitan Perth sites recorded minima below 10 °C, and Jandakot Aerodrome recorded a minimum of 0.5 °C on the 31st, its fourth lowest May minimum temperature in 23 years of record, and the lowest temperature recorded in the Perth metropolitan area during May 2013.

Perth Metro's mean daily minimum temperature in May was 10.6 °C, which is near the average. Daily minima ranged from a mild 17.5 °C on the 2nd to a cold of 3.5 °C on the 31st, Perth Metro's coldest morning for over nine months, since a minimum of 2.9 °C was recorded on 9 August 2012.

Sunshine

Perth Metro's mean daily sunshine hours for May was 7.2 hours, which was slightly higher than the average of 6.9 hours.

 

Further information

Media
(03) 9669 4057
Enquiries

Extremes in May 2013
Hottest day 27.8 °C at Pearce RAAF on the 1st
Warmest days on average 22.0 °C at Swanbourne
Coolest days on average 18.5 °C at Bickley
Coldest day 11.6 °C at Bickley on the 30th
Coldest night 0.5 °C at Jandakot Aero on the 31st
Coolest nights on average 9.1 °C at Jandakot Aero
Warmest nights on average 14.8 °C at Rottnest Island
12.3 °C at Swanbourne
Warmest night 19.7 °C at Rottnest Island on the 1st
Warmest on average overall 17.8 °C at Rottnest Island
17.3 °C at Swanbourne
Coolest on average overall 14.4 °C at Bickley
Wettest overall 189.6 mm at Bickley
Wettest day 61.6 mm at Rottnest Island on the 8th
56.8 mm at Swanbourne on the 8th
Highest wind gust 106 km/h at Rottnest Island on the 8th
94 km/h at Bickley on the 8th



Record lowest May temperature
Lowest temperature
in May 2013 (°C)
Previous coolest
for May
Years of
record
Average for
May
Swanbourne 5.0 on the 31st 6.0 on the 25th in 2009 20 12.6



Summary statistics for May 2013
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2013
Diff
from
average
Highest for
May
2013
Mean for
May
2013
Diff
from
average
Lowest for
May
2013
Total for
May
2013
Average
for
May
Rank of
May
2013
Fraction of
May
average
Bickley 18.5 -1.0 23.8 1st 10.0 -0.2 3.9 31st 189.6 130.0 high 146%
Champion Lakes 21.0   25.4 1st 12.0   3.9 31st 124.2
Garden Island HSF 20.8 -0.8 23.8 7th 13.7 -0.3 9.2 31st 150.8 79.2 high 190%
Jandakot Aero 21.4 -0.7 25.2 1st 9.1 -0.3 0.5 31st 164.2 107.7 high 152%
Perth Airport 21.8 0.0 26.9 1st 10.6 +0.2 1.6 31st 108.2 99.4 average 109%
Perth Metro 21.7 -0.8 25.7 1st 10.6 +0.1 3.5 31st 138.2 116.8 high 118%
Rottnest Island 20.7 -0.5 24.2 1st 14.8 -0.5 9.6 31st 170.4 100.4 high 170%
Swanbourne 22.0 -0.3 25.5 5th 12.3 -0.3 5.0 31st 152.2 91.0 v high 167%

Daily maximum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley23.818.619.320.222.620.221.417.217.516.216.617.917.618.819.420.116.517.218.615.518.818.817.718.519.422.120.117.516.211.6
Champion Lakes25.421.922.123.124.522.323.220.420.219.019.020.020.021.421.922.119.320.320.418.421.021.820.221.522.323.622.021.018.414.1
Garden Island HSF23.322.621.323.123.521.223.820.320.319.418.619.520.721.721.921.119.919.820.418.419.020.821.022.022.822.421.918.919.014.9
Gosnells City26.822.822.224.025.325.021.621.320.519.820.521.122.523.423.420.721.221.921.522.622.524.425.523.220.919.014.8
Jandakot Aero25.223.022.223.324.923.124.420.620.920.119.720.320.522.122.322.320.119.821.119.020.922.020.621.823.124.022.520.119.014.3
Medina Research Centre26.323.722.025.525.723.025.121.020.919.719.520.320.422.323.021.521.621.022.321.224.623.020.319.014.5
Pearce RAAF27.824.723.226.022.224.821.621.920.420.320.820.522.022.924.720.920.721.519.121.021.220.122.025.120.920.215.2
Perth Airport26.923.222.923.425.322.424.621.620.819.720.121.020.821.922.822.820.020.521.919.421.522.020.922.023.224.823.420.619.614.9
Perth Metro25.722.922.623.625.422.324.120.820.820.119.720.721.121.822.623.420.320.521.719.221.221.620.822.023.224.923.020.019.614.6
Rottnest Island24.222.920.721.622.122.123.520.820.519.919.419.219.921.522.021.220.218.920.417.719.021.119.820.823.122.821.719.118.715.2
Swanbourne24.223.623.024.825.522.323.921.121.521.320.521.921.722.623.524.020.820.821.319.420.622.621.422.723.624.123.121.319.714.6

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.
The temperatures in this table are coloured by
their difference from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C difference from average


Daily minimum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley15.714.512.012.412.713.613.314.310.09.410.88.79.07.97.09.110.79.18.48.48.69.56.76.97.110.712.410.68.89.23.9
Champion Lakes15.616.913.414.515.914.413.916.513.311.313.08.410.812.010.212.812.310.99.711.68.78.99.410.511.113.913.612.811.711.43.9
Garden Island HSF14.818.316.015.215.114.315.317.113.114.715.011.312.612.213.513.515.113.111.512.012.712.812.112.413.315.615.113.312.112.09.2
Gosnells City15.016.913.013.515.213.815.113.011.213.07.510.111.911.212.112.69.08.610.97.37.98.513.010.212.010.711.43.0
Jandakot Aero13.417.211.310.011.511.611.116.313.412.711.74.56.18.04.66.110.07.26.19.95.25.55.44.69.69.39.89.98.310.80.5
Medina Research Centre13.711.813.013.012.212.016.313.413.613.15.98.68.86.99.413.010.85.87.07.112.410.79.411.02.1
Pearce RAAF12.617.512.911.313.911.913.116.411.512.213.55.95.49.710.612.28.68.910.65.54.98.34.69.811.210.311.10.6
Perth Airport13.516.810.711.212.713.913.716.513.012.811.55.57.610.510.311.211.99.58.011.16.05.88.76.09.614.412.811.49.210.81.6
Perth Metro14.417.512.411.512.813.013.716.513.213.411.96.37.09.86.38.512.210.39.111.07.56.56.36.78.211.512.812.010.011.33.5
Rottnest Island19.718.316.815.916.017.917.717.213.013.815.014.314.613.814.916.614.413.213.411.513.714.813.814.015.015.715.914.713.210.59.6
Swanbourne16.317.814.614.213.814.914.916.513.614.113.69.79.410.710.213.015.412.410.511.29.59.58.59.911.013.814.313.110.610.85.0

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.
The temperatures in this table are coloured by
their difference from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C difference from average


Daily rainfall
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley - 26.2 9.4 - - - - 28.0 45.4 8.4 11.0 - - - 0.2 - 5.2 0.6 - 8.0 0.2 0.2 - 0.2 - - 0.2 11.6 6.4 24.4 4.0
Champion Lakes - 20.2 8.2 - - - - 36.8 15.8 6.4 4.2 - - - - - 8.6 0.2 - 8.0 0.2 - - - - - 1.4 1.0 1.4 8.6 3.2
Garden Island HSF - 12.4 4.0 - - - - 53.0 13.6 7.0 4.6 - - - - - 12.4 1.2 - 10.4 - 0.2 - - - - 4.4 3.8 4.4 9.4 10.0
Gosnells City - 17.8 7.4 - - - - 35.4 21.4 4.6 9.6 - - - - - 5.2 0.2 »» 8.2 - - 1.0 - - - 0.8 1.2 1.1 24.6 2.8
Jandakot Aero - 12.0 6.8 - - - - 51.8 20.6 6.6 12.6 - - - - - 9.0 0.6 - 5.2 - - - - - - 1.2 5.4 13.0 14.2 5.2
Jarrahdale - 19.4 14.2 0.2 0.4 - 0.2 41.4 33.0 24.8 8.2 0.2 0.2 0.2 0.4 0.2 7.8 0.2 - 4.8 0.4 0.2 0.2 0.2 0.2 - 1.2 0.6 3.6 23.0 2.4
Medina Research Centre »» 8.2 5.4 0.2 - - - 40.0 11.6 9.4 5.6 0.1 0.1 - - - 16.0 »» »» 8.2 »» 0.2 - - »» »» »» »» 4.4 13.6 7.6
Pearce RAAF - 5.8 3.6 -

- 11.0 22.4 5.0 7.2 - - - -
2.0 - 0.8 8.0 0.4 - - - -
- 9.4 - 16.4 1.0
Perth Airport - 12.2 3.8 - - - - 26.2 17.6 4.2 8.2 0.2 - - - - 3.8 - 0.2 7.8 - - - - - - - 8.2 - 14.0 1.8
Perth Metro - 10.8 5.0 - - - - 43.6 22.8 5.4 7.2 - - - - - 9.4 0.6 - 6.0 1.0 - - - - - - 9.4 - 13.6 3.4
Roleystone - 22.0 9.0 - - - - 39.6 26.2 8.2 8.0 - - - - - 6.0 1.4 5.2 2.8 - - - - - - - 3.4 0.8 12.2 3.4
Rottnest Island - 1.8 4.0 - - - - 61.6 10.8 2.0 0.4 - - - - - 18.2 18.4 0.4 20.2 - - - - - - 11.2 3.4 6.6 6.8 4.6
Serpentine - 14.0 10.8 0.2 - - - 28.8 23.8 12.0 5.4 - - - - - 7.6 - - 5.2 - - - - - - 2.6 - 2.0 19.6 3.6
Swanbourne - 9.8 2.6 0.2 - - - 56.8 18.2 5.8 3.4 - 0.2 - - - 7.6 0.6 0.2 8.2 0.2 0.2 - - - - 1.8 15.8 4.6 8.8 7.2

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 2 pm on Friday 31 May 2013. 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, as they cannot then be calculated reliably.
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.

The ACORN-SAT dataset is being used for temperature area averages from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.

Further information

Media
(03) 9669 4057
Enquiries