Perth in June 2012: A mild cloudy month with near average rainfall

  • Rainfall: Near average at most sites
  • Maximum temperature: Near average
  • Minimum temperature: Above average at most sites

Rainfall

Rainfall totals in June 2012 were close to average at most sites in the Perth metropolitan area, apart from Gosnells City which saw below average rainfall.

A strong high moving into the Bight brought generally dry conditions to the Perth area in the first days of June until a slow moving trough off the west coast, associated with a near stationary low to the southwest of the state, brought showers and thunderstorms with moderate falls to the area on the 6th. The trough moved gradually eastward over land during the morning of the 7th, with severe thunderstorms developing over Perth in the late morning and early afternoon, and a tornado was reported close to midday in the suburbs of Dianella and Morley, causing substatial damage. Light showers persisted over the next few days, before a rapidly deepening tropical low off the northwest coast of Western Australia moved south-southeastward close to the west coast during the morning on the 10th and crossed the Southwest district during the afternoon, bringing severe wind gusts and moderate rainfall to the Perth area. A cold front moved through the Perth metropolitan area on the 11th, bringing further rainfall and more severe wind gusts before a rapidly developing cold front and deep low pressure system moved through the Southwest Land Division (SWLD) during the afternoon and evening of the 12th, bringing moderate to heavy falls and more severe winds to the Perth area. A persistent westerly flow was maintained over the Perth region through to the 18th, bringing consistent, though generally light, rainfall, with cold fronts on the 19th and 20th bringing moderate falls. A ridge over the south of the state resulted in generally dry conditions from the 22nd through to the 25th, before a cloudband and cold front brought moderate showers to the area on the 26th, then lighter showers persisted to the 28th.

Perth Metro recorded 140.8 rainfall on 18 rain days in June 2012, below the long-term average for June of 175.7 mm on 15.1 rain days, but in the near average range. Historically, June rainfall extremes have ranged from 24.6 mm in 2006 to 476.1 mm in 1945 while last June (2011), Perth Metro recorded 171.4 mm on 14 rain days. The wettest day during June 2012 at Perth Metro was the 13th with 21.8 mm. For the year so far (January to June), Perth Metro has recorded 301.6 mm of rainfall on 43 rain days. The average for the six month January to June period is 378.5 mm on 41.6 rain days, while last year (2011), Perth Metro recorded 306.4 mm on 35 rain days.

Maximum temperature

Mean maximum temperatures in June 2012 were close to average across the Perth metropolitan area and generally between 19 °C and 20 °C, though Bickley recorded the lowest mean maximum with 15.8 °C.

Warm conditions were observed across Perth from the 3rd to 5th due to a strong high to the south of the state directing warm northerly winds over the region, with all sites in Perth recording their warmest day of the month on the 3rd registering temperatures in the low to mid-20s. Maximum temperatures dropped on the 6th as a cloudband moved across the region, with temperatures dropping to the mid-teens at most sites. Slightly warmer than normal conditions prevailed from the 7th to the 12th in a generally northerly flow, before a series of strong cold fronts resulted in cooler temperatures from the 13th to 16th. Milder temperatures into the low twenties were reported from the 17th to 19th as northwesterly winds prevailed, before cold days were observed on the 20th and 21st in the wake of a cold front with most sites observing their coolest day of June 2012 on these dates. Maxima on the 20th and 21st dropped to the mid-teens at most sites, and Bickley recorded the lowest maximum temperature for the month in the metropolitan area with 11.3 °C. Mostly cooler than normal temperatures persisted for the remainder of the month.

Perth Metro's mean daily maximum temperature in June was 19.6 °C, which was the warmest June for four years since 19.7 °C was recorded in 2008. The average for June is 19.3 °C. Daily maxima ranged from a cool 15.3 °C on the 25th to a warm 24.2 °C on the 3rd. Perth Metro's above average mean monthly maximum temperature in June was the fourth consecutive month to record an above average mean maximum, and in fact only three of the past 24 months, since July 2010, have observed below above average mean monthly day-time temperatures.

Perth Metro's mean daily maximum temperature for the year so far (January to June 2012) is 27.5 °C, the 3rd warmest start to the year since records commenced in 1897. The warmest January to June period on record at Perth Metro was in 2011 with a mean maximum of 28.1 °C, while the average for this period is 26.6 °C. Perth Metro’s 2nd warmest January to June period on record was in 1978 with a mean of 27.6 °C.

Minimum temperature

Mean minimum temperatures in June 2012 were generally above average across the Perth metropolitan area with mean minima mostly close to 10 °C.

Relatively warm nights were observed through much of the first half of June 2012, with overnight temperatures only dropping below normal, at most sites, on the 2nd and following the strong cold fronts on the 14th and 15th. Most metropolitan sites recorded their warmest nights on the 4th or 5th, or 10th or 11th, with the highest minimum in the Perth region for the month of 17.7 °C recorded at Rottnest Island on the 4th. This followed the warmest day of the month as cloud moved over the southwest in a northerly airflow. A cold spell was observed from the 20th through to the 23rd as a ridge developed in the wake of a cold front, with all Perth sites observing their coldest night for the month on the 21st or 22nd. The lowest temperature recorded during June 2012 in the Perth metropolitan area was 0.0 °C at Jandakot Aerodrome on the 22nd.

Perth Metro's mean daily minimum temperature in June was 10.2 °C, which is the warmest June in eight years, since a mean of 10.6 °C was recorded in 2004. The average for June is 8.6 °C. Daily minima ranged from a cold 1.8 °C on the 22nd, the coldest night in June for 2 years at Perth Metro, to a mild 16.3 °C on the 11th. Perth Metro observed minimum temperatures of 15.7 °C on the 4th, 15.4 °C on the 5th, and 16.3 °C on the 11th, and prior to 2012, the highest June minimum temperature recorded at the Perth Metro observation site in Mt Lawley was 15.4 °C on both 13 June 2000 and 4 June 2005. Thus, during June 2012, the highest minimum temperature record at the Mt Lawley site was broken or equalled on three occasions. Records at Mt Lawley commenced in 1994.

Sunshine

Perth recorded an average daily sunshine of 4.4 hours in June 2012, which was the least sunniest June for 21 years since 4.4 hours was recorded in 1991. The average sunshine for June is 6.0 hours per day. The sunshine hours for last June (2011) was 5.5 hours. The least sunniest June on record was in 1945 with 2.9 hours per day, which was also Perth Metro’s wettest ever month on record with 476.1 mm on 23 rain days.

Other Phenomena

Significant weather events due to a series of cold fronts and low pressure systems were observed across the SWLD during the middle part of June 2012. A summary of these events is included below, but for further information please refer to Special Climate Statement 40 which will be available soon.

A tornado was reported in the suburbs of Dianella and Morley as a trough moved across the Lower West. The Fire and Emergency Services Authority (FESA) reported significant damage to approximately 20 homes in Dianella, whilst businesses were also impacted with a video store in Morley having its roof damaged and windows broken by winds estimated to be in excess of 120 km/h. Western Power reported up to 5000 homes lost power as a result of the tornado. Tornadoes are a regular feature of winter weather in southwest Western Australia with an average of approximately six reported per year; however, these tornadoes are normally associated with the passage of cold fronts. In this instance, the tornadoes were not associated with a cold front, and this is highly unusual in winter in southwest Western Australia.

Very windy conditions were observed in the Lower West, Southwest, and South Coastal districts on the 10th as a low crossed the Southwest district during the afternoon. Rottnest Island, Garden Island, Jandakot Aerodrome, Bickley, Swanbourne, Pearce RAAF, and Champion Lakes all observed wind gusts in excess of 90 km/h. Widespread property damage was reported in western parts of the SWLD, including the Perth region, with a significant number of trees downed and Western Power reported unprecedented damage to the electricity supply grid southwest of a line from Geraldton to Ravensthorpe. A significant storm surge was reported along the SWLD west coast with sea levels up to approximately 0.8 m above the Highest Astronomical Tide (HAT ). The WA Department of Transport Fremantle Fishing Boat Harbour tide gauge observed a record maximum sea level of 2.12 m, 0.76 m above the HAT, and 0.14 m above the previous highest sea level recorded by the gauge of 1.98 m on 16 May 2003. Sea level recordings at Fremantle extend back to 1897. The Swan River at Perth (Barrack Street) recorded a high tide of equal to or greater than 1.6 m between 1359 and 1615 WST, with a peak of 1.71 m at approximately 1500 WST. Previous experience suggests inundation of Riverside Drive, next to the Swan River and Perth CBD, occurs when the tide reaches 1.6 m or greater, and reports confirmed that the river foreshore and Riverside Drive were inundated during the afternoon.

Water levels in the Swan River at Perth (Barrack Street) again reached and exceeded 1.6 m between 1009 and 1506 WST on the 11th as a cold front moved through the SWLD, with another peak of 1.71 m at approximately 1300 WST. Despite a similar peak river height to the previous day, this event persisted for several hours longer forcing Riverside Drive to be closed due to inundation. Jandakot Aerodrome again recorded a wind gust greater than 90 km/h.

Severe winds were again observed in the Perth area on the 12th and 13th as a deep low and cold front moved through the SWLD. The highest wind gust reported during this event in the metropolitan area was 113 km/h at Rottnest Island in the evening on the 12th, whilst Swanbourne, Ocean Reef, Garden Island, Jandakot Aerodrome, and Bickley all reported gusts over 90 km/h as the cold front moved through. The impact of the severe winds saw trees uprooted and houses suffer roof damage through southwest WA whilst Western Power reported that 17,000 homes were left without power with 30 power lines brought down. This was additional to the 10,000 homes that were yet to be reconnected after the event on the 10th. A third notable storm surge was reported during this event though at most sites the surge was weaker than the previous two events. The Swan River at Perth (Barrack Street) equalled or exceeding 1.6 m for only a short period between 0322 and 0347 WST, with a peak of 1.61 m.

Further information

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Extremes in June 2012
Hottest day 25.5 °C at Gosnells City on the 3rd
Warmest days on average 19.9 °C at Gosnells City
Coolest days on average 15.8 °C at Bickley
Coldest day 11.3 °C at Bickley on the 20th
Coldest night 0.0 °C at Jandakot Aero on the 22nd
Coolest nights on average 9.0 °C at Bickley
Warmest nights on average 13.8 °C at Rottnest Island
Warmest night 17.7 °C at Rottnest Island on the 4th
16.5 °C at Medina on the 4th
Wettest overall 253.0 mm at Mundaring
Wettest day 43.0 mm at Mundaring on the 13th
Highest wind gust 119 km/h at Rottnest Island on the 10th

Summary statistics for June 2012
Maximum temperatures
for June
(°C)
Minimum temperatures
for June
(°C)
Rainfall
for June
(millimetres)
Mean for
June
2012
Diff
from
average
Highest for
June
2012
Mean for
June
2012
Diff
from
average
Lowest for
June
2012
Total for
June
2012
Average
for
June
Rank of
June
2012
Fraction of
June
average
Bickley 15.8 -0.2 21.2 3rd 9.0 +0.9 3.9 21st 228.6 205.6 average 111%
Champion Lakes 18.8   23.7 3rd 11.1   3.9 21st 149.8
Garden Island HSF 18.9 -0.2 23.1 3rd 12.8 +0.7 7.7 22nd 139.6 121.8 high 115%
Gosnells City 19.9 +0.3 25.5 3rd 10.6 +0.8 3.2 22nd 128.3 174.1 low 74%
Jandakot Aero 19.3 +0.4 24.3 3rd 9.2 +1.8 0.0 22nd 168.4 162.4 average 104%
Medina Research Centre 19.5 +0.2 24.3 3rd 10.3 +1.3 2.1 22nd 153.2 148.3 average 103%
Pearce RAAF 19.2 +0.4 24.1 3rd 10.1 +0.7 1.7 22nd 148.0 135.1 average 109%
Perth Airport 19.3 +0.4 24.4 3rd 10.1 +1.1 1.3 22nd 132.8 162.0 average 82%
Perth Metro 19.6 +0.3 24.2 3rd 10.2 +1.6 1.8 22nd 140.8 175.7 average 80%
Rottnest Island 19.1 +0.4 23.4 3rd 13.8 +0.5 9.8 21st 123.2 151.3 average 81%
Swanbourne 19.6 +0.3 24.7 3rd 11.5 +0.9 4.9 22nd 148.8 131.2 average 113%

Daily maximum temperature
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley17.416.721.218.619.712.515.617.815.817.515.915.213.014.315.414.717.619.616.711.312.814.114.115.311.716.916.314.714.216.9
Champion Lakes19.320.523.722.222.517.119.320.419.921.019.919.015.016.317.817.720.322.419.414.415.318.016.618.416.020.018.617.417.319.2
Garden Island HSF18.319.223.122.022.716.519.720.620.221.520.319.316.617.818.017.420.421.320.116.315.216.417.119.316.320.118.917.816.818.6
Gosnells City21.021.025.523.023.716.922.020.521.419.917.818.018.521.423.721.015.315.917.520.116.620.720.118.118.020.5
Jandakot Aero19.720.324.322.923.516.920.520.720.321.320.419.516.817.418.217.820.522.920.415.715.616.716.919.416.020.319.618.317.319.4
Medina Research Centre19.220.824.322.423.616.620.921.420.521.520.419.716.118.418.717.521.523.520.415.515.817.117.519.915.720.519.718.417.420.3
Pearce RAAF19.020.424.123.223.517.120.920.119.121.220.219.116.517.018.217.920.922.620.214.515.416.117.019.815.721.219.318.216.719.6
Perth Airport20.020.324.421.723.216.819.020.619.321.320.419.516.517.418.517.920.723.420.715.516.017.117.319.115.820.820.118.117.720.0
Perth Metro19.620.624.222.923.217.420.421.019.221.520.819.816.918.218.918.221.523.621.115.916.117.117.618.915.320.819.819.317.420.2
Rottnest Island18.319.923.422.122.317.320.821.419.221.920.319.616.917.418.417.220.421.720.917.114.816.316.918.916.520.319.618.416.518.5
Swanbourne19.521.624.722.723.317.020.921.319.121.720.520.017.318.319.217.521.223.520.815.816.417.217.819.515.321.019.719.517.619.4

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)123456789101112131415161718192021222324252627282930
Bickley12.18.610.111.710.110.610.010.610.412.613.19.09.26.57.811.211.27.311.56.23.94.44.76.66.98.111.18.97.17.3
Champion Lakes13.510.813.616.416.115.713.111.011.613.815.311.412.39.28.09.713.810.113.17.63.94.36.39.310.313.513.611.27.97.1
Garden Island HSF14.711.513.916.916.614.713.113.814.716.316.413.114.19.510.712.914.312.615.410.08.87.77.811.711.813.815.413.410.39.1
Gosnells City12.08.511.015.015.814.913.110.015.515.312.58.010.013.58.813.17.63.43.24.011.213.213.011.37.15.0
Jandakot Aero9.04.411.116.115.813.512.711.47.414.315.410.512.87.95.710.713.45.510.84.90.20.01.77.49.112.411.812.35.23.1
Medina Research Centre11.06.012.316.516.113.312.511.99.815.915.712.313.88.66.911.38.912.66.72.52.12.46.89.912.914.013.37.04.5
Pearce RAAF12.58.311.615.215.115.012.911.49.115.613.910.812.09.76.610.612.08.59.67.22.41.72.68.211.813.212.410.96.84.2
Perth Airport11.86.811.815.615.515.312.711.610.415.715.09.712.79.07.411.012.79.610.17.01.51.32.78.910.311.912.410.46.35.5
Perth Metro11.67.412.515.715.414.512.811.611.115.316.311.013.09.57.211.112.96.812.27.82.71.82.28.57.111.811.212.37.95.4
Rottnest Island15.912.714.117.716.914.713.714.616.416.115.612.312.610.212.714.413.915.016.510.69.810.911.012.913.914.715.214.112.613.0
Swanbourne13.58.913.216.315.412.912.312.212.215.315.812.313.29.210.112.413.19.914.19.25.44.95.38.610.412.814.514.49.47.8

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)123456789101112131415161718192021222324252627282930
Bickley 3.0 0.2 - - - - 25.2 32.4 0.8 5.8 32.4 19.6 40.0 0.2 7.4 2.0 5.8 0.2 10.0 20.2 6.2 0.2 0.2 - - - 8.4 7.4 1.0 -
Champion Lakes 0.6 - - - - - 13.0 28.8 - 3.2 16.0 14.4 18.8 - 13.2 1.0 1.2 - 12.8 4.6 7.0 - - - - - 9.4 5.6 0.2 -
Garden Island HSF 3.4 - - - - - 14.0 12.0 3.2 3.6 4.4 10.4 11.4 2.6 11.6 6.6 3.4 0.2 11.8 13.0 14.2 0.2 - 0.2 - - 12.0 1.0 0.4 -
Gosnells City 1.2 - - - - 0.2 11.2 »» 8.8 4.2 10.4 9.4 17.9 »» 10.0 1.1 3.4 0.2 15.4 13.0 8.2 0.1 -
- - 7.6 5.4 0.6 -
Jandakot Aero 1.4 - - - - 0.6 18.6 22.8 - 6.2 16.6 15.8 23.2 0.2 9.8 1.6 2.0 - 15.2 10.8 8.8 - - - - - 9.2 4.6 1.0 -
Jarrahdale 6.8 0.2 0.2 - - - 24.2 25.6 0.2 4.2 29.6 19.8 31.2 0.2 4.8 0.2 3.6 0.6 18.8 23.0 14.6 0.2 0.2 - 0.2 - 19.4 3.0 1.4 0.2
Medina Research Centre 6.0 - - - - 0.8 13.2 14.0 1.0 4.2 8.5 10.8 19.0 1.4 19.6 4.7 1.0 - 10.0 13.4 8.6 - - - - - 16.0 1.0 - -
Mundaring 25.4 0.2


0.4 32.2 22.0 0.6 5.8 22.2 24.4 43.0 0.6 17.6 4.0 4.6 0.2 11.8 20.0 7.4 0.2 0.2


5.2 3.4 1.4 0.2
Pearce RAAF 8.4 - - - - - 15.8 12.0 »» »» 9.8 7.2 24.4 1.2 6.0 »» »» 3.0 13.0 26.4 9.6 0.2 - - - - 2.0 3.2 5.8 -
Perth Airport 6.6 - - - - - 14.4 10.4 0.2 4.2 6.0 16.6 27.2 0.2 8.6 1.0 2.8 - 8.0 8.0 11.8 - - - - - 4.4 1.0 1.4 -
Perth Metro 7.6 - - - - - 13.4 15.8 0.6 4.4 5.0 16.6 21.8 0.4 9.6 3.0 3.6 - 8.4 8.8 11.4 - - - - - 9.0 1.2 0.2 -
Roleystone 2.4



0.2 19.2 16.4
5.6 25.0 14.0 33.4 - 13.0 2.0 4.2 0.2 14.6 8.8 7.0




9.0


Rottnest Island 0.6 - - - - 0.2 17.0 4.4 4.4 7.8 4.6 5.2 8.2 9.4 7.6 8.2 6.4 - 9.0 9.0 8.2 - - - - - 11.8 0.8 0.4 -
Serpentine 6.8 0.2 - - - 0.2 18.8 12.2 0.2 3.4 11.8 13.6 21.6 - 5.4 0.2 1.2 - 14.4 6.0 11.6 - - - - - 15.4 1.2 0.6 -
Swanbourne 7.6 0.2 - - - 0.8 18.2 4.6 1.2 6.4 13.0 11.6 14.8 1.2 12.4 6.6 4.6 - 11.0 8.2 16.2 0.2 0.2 - - - 8.0 1.2 0.4 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

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 8 am on Monday 2 July 2012. 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.

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 minimum 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