Monday, 1 August 2011 - Monthly Climate Summary for Perth - Product code IDCKGC11L0

Perth in July 2011: An average July

• Rainfall: Near average to above average for Perth.
• Maximum temperature: Near average across Perth.
• Minimum temperature: Near average across Perth.

Details Extremes Records Summaries Important notes the top

Rainfall

Rainfall in July 2011 was near average for most Perth Metropolitan sites, though it was above average on Rottnest and Garden Island, as well as in the hills, with monthly rainfall totals across the metropolitan area generally in the 120-220 mm range.

A pre-frontal trough and cold front, followed by unstable westerly winds produced persistent rainfall from 30 June to 3 July, with daily rainfall totals of 20 to 40 mm recorded in the Perth metropolitan area in the 24 hours to 9 am on 1 July. A cloudband over the region on the 10th and 11th brought mainly light rainfall, with some isolated moderate falls to the Perth area, whilst a cold front on the 15th brought further moderate falls. After a short break, several cold fronts produced light to moderate rainfall between the 20th and 26th, though Rottnest Island received an exceptionally heavy fall from a thunderstorm with daily total of 66.8 mm on the 21st, the third highest July daily rainfall recorded at Rottnest Island, and the highest daily total in the Perth area for the month. Flash flooding occurred at Fremantal on the 22nd. Several cold fronts and a low pressure system produced more downpours and windy weather at the last few days of July.

Perth Metro recorded 161.0 mm of rainfall on 18 days during July 2011, which was near average. Despite this, the total rainfall for the seven months from January to July 2011 at Perth Metro remained below average, with 467.4 mm recorded on 53 rain days. The long-term average for this period is 548.7 mm on about 59 days, while the total for the same period last year was 347.6 mm on 38 days.

Maximum temperature

Daytime temperatures during July 2011 were near average across the Perth metropolitan area. Mean daily maximum temperatures were in the 15 to 19 °C range, and generally within 0.5 °C of long-term means. The warmest day of the month was the 14th as Gosnells City recorded the highest daily maximum in the Perth metropolitan area for July 2011 with 22.8 °C. The coldest day of the month was the 11th when Bickley registered a daily maximum temperature of 9.6 °C, which was the coldest July day in 18 years of record.

Perth Metro's mean maximum temperature in July 2011 was 18.3 °C, which is the same as the long-term average. Daily maxima ranged from a cold 13.0 °C on the 11th, to a mild 22.0 °C on the 14th.

Minimum temperature

Overnight temperatures during July 2011 were near average across the Perth area. Mean daily minimum temperatures were in the 8 to 12 °C range, and generally within 1 °C of normal. The coldest night of the month for many sites was the 4th, with several sites registering daily minimum temperatures 5 °C or lower, and Jandakot Aerodrome recorded the lowest minimum in Perth in July 2011 with -0.4 °C. The warmest night of the month for the Perth area was the 31st, and Jandakot Aerodrome recorded the warmest July night in 22 years of record.

Perth Metro's mean minimum temperature in July was 8.5 °C, which is near the average of 7.8 °C. Minima at Perth Metro ranged from a cold 1.3 °C on the 4th, to a mild 15.4 °C on the 31st, the highest overnight minimum for July at Perth Metro in 10 years, since 15.4 °C was recorded on 30 July 2001.

Wind and sunshine

Cold fronts brought significant winds to the Perth metropolitan area in the second half of July, with a tornado reported at Serpentine on the 22nd with the passage of a cold front. Severe wind gusts were observed at Rottnest Island on the 27th and the 31st, with the highest wind gust of 126 km/h from the northwest at 1713 WST on the 27th when a strong cold front crossed the Perth region. This gust was the strongest reported in the metropolitan area in July 2011. Significant roof damage was reported at Rockingham with minor damage also reported in Kalamunda.

Perth recorded an average daily sunshine of 5.2 hours in July 2011, which is the least sunshine hours for Perth in July for three years, since 5.1 hours per day was recorded in 2008. The average sunshine for Perth in July is 6.1 hours per day.

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Extremes in July 2011
Hottest day	22.8 °C at Gosnells City on the 14th
Warmest days on average	18.8 °C at Gosnells City
Coolest days on average	15.0 °C at Bickley
Coldest day	9.6 °C at Bickley on the 11th
Coldest night	-0.4 °C at Jandakot Aero on the 4th
Coolest nights on average	7.5 °C at Jandakot Aero
Warmest nights on average	12.3 °C at Rottnest Island 9.9 °C at Swanbourne
Warmest night	16.3 °C at Rottnest Island on the 25th 15.4°C at Perth Metro on the 31st
Wettest overall	270.0 mm at Bickley
Wettest day	66.8 mm at Rottnest Island on the 21st 42.3 mm at Pickering Brook on the 31st
Highest wind gust	126 km/h at Rottnest Island on the 27th

etails Extremes Records Summaries Important notes the top

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Record lowest July daily maximum temperature
	Lowest daily maximum temperature in July 2011 (°C)		Previous lowest for July		Years of record	Average for July
Bickley	9.6	on the 11th	9.8	on the 9th in 2010	18	15.0

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Record highest July daily minimum temperature
	Highest daily minimum temperature in July 2011 (°C)		Previous highest for July		Years of record	Average for July
Jandakot Aero	15.1	on the 31st	15.0	on the 3rd in 1994	22	6.8

Details Extremes Records Summaries Important notes the top

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Summary statistics for July 2011
	Maximum temperatures for July (°C)				Minimum temperatures for July (°C)				Rainfall for July (millimetres)
	Mean for July 2011	Diff from average	Highest for July 2011		Mean for July 2011	Diff from average	Lowest for July 2011		Total for July 2011	Average for July	Rank of July 2011	Fraction of July average
Bickley	15.0	0.0	18.7	14th	7.8	+0.7	3.9	4th	270.0	221.8	high	122%
Champion Lakes	17.5		21.1	14th	9.8		3.8	4th	143.6
Garden Island HSF	17.5		20.4	24th	11.5		7.4	4th	175.6	121.8	high	144%
Gosnells City	18.8	+0.2	22.8	14th					137.0	164.5	low	83%
Jandakot Aero	18.2	+0.4	22.3	24th	7.5	+0.7	-0.4	4th	181.0	178.3	average	102%
Medina Research Centre	18.0	-0.2	22.5	24th	8.9	+0.6	1.3	4th
Pearce RAAF	17.6	-0.2	21.9	24th	8.7	+0.2	0.7	4th
Perth Airport	18.4	+0.5	22.1	14th	8.6	+0.6	0.2	4th	160.2	159.1	average	101%
Perth Metro	18.3	0.0	22.0	14th	8.5	+0.7	1.3	4th	161.0	169.7	average	95%
Rottnest Island	17.3	-0.4	21.2	24th	12.3	0.0	9.2	3rd	181.6	143.9	high	126%
Swanbourne	18.2	-0.1	21.8	14th	9.9	+0.3	4.7	4th	155.2	151.5	average	102%

Details Extremes Records Summaries Important notes the top

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Daily maximum temperature
Central Coast (09)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Bickley	13.9	13.1	11.9	13.3	13.1	14.0	11.6	13.7	12.7	10.7	9.6	13.4	16.2	18.7	15.1	15.6	15.4	16.0	16.2	16.2	17.1	15.5	15.8	18.5	16.9	17.2	18.6	16.0	15.4	16.4	16.8
Champion Lakes	16.4	16.0	14.2	15.3	15.8	16.2	14.2	15.6	15.4	14.1	12.9	16.4	19.9	21.1	17.8	17.7	17.8	18.1	19.0	18.1	18.3	16.3	18.2	20.9	19.4	19.2	20.5	19.2	19.0	19.4	19.4
Garden Island HSF	17.3	16.5	14.1	15.1	14.6	15.4	15.1	17.0	16.9	15.3	13.6	16.7	18.7	20.3	18.7	16.7	18.6	19.1	18.2	17.1	17.6	17.1	16.9	20.4	18.1	19.4	19.9	19.4	19.2	19.9	19.3
Gosnells City	17.5	17.0	15.1	16.1	17.1	17.3	15.4	17.1	16.5		14.4	17.8	20.5	22.8	18.2	18.7	19.2		20.2	19.4		19.2	20.4	22.4	19.4	21.0	22.0	20.5	20.0	21.0	20.9
Jandakot Aero	17.9	16.9	14.8	15.6	16.1	17.0	15.4	17.1	16.1	14.2	12.8	17.4	20.2	21.9	19.2	17.9	18.8	18.8	19.7	19.3	19.1	17.2	19.1	22.3	18.6	19.7	21.5	20.0	19.9	20.6	20.4
Medina Research Centre	17.2	16.7	14.9	15.6	16.1	16.8	14.5	17.9	16.0	14.9	12.8	17.1	20.7	22.4	19.0	18.6	19.5	19.7	20.2	18.0	19.7	17.6	17.8	22.5	17.9	19.3	21.5	20.4
Pearce RAAF	17.4	15.7	14.4	15.0	15.8	16.5	14.9	16.3	15.8	12.8	13.2	16.9	19.1	21.3	17.7	18.2	17.4	17.6	18.7	18.9	18.0	18.2	19.0	21.9	19.3	19.9			19.2	20.7	20.4
Perth Airport	17.4	16.9	14.9	15.9	16.4	17.3	16.0	16.3	16.5	14.1	12.8	17.1	20.0	22.1	18.7	18.9	18.8	19.2	20.2	18.6	18.9	18.7	19.8	21.7	18.6	20.3	21.8	20.1	20.4	20.9	20.7
Perth Metro	17.2	16.7	14.3	15.4	16.4	16.4	15.3	16.6	16.6	14.0	13.0	17.0	19.9	22.0	19.1	18.4	18.8	19.1	19.9	18.3	19.8	18.7	19.9	21.7	18.8	20.5	21.4	20.3	20.5	21.0	21.1
Rottnest Island	17.3	16.2	14.4	13.8	14.6	15.2	14.4	15.8	15.3	13.8	13.0	15.8	18.4	20.1	19.3	16.5	17.0	17.6	18.0	17.3	17.3	18.3	16.6	21.2	19.6	19.1	20.0	19.4	19.7	20.1	19.7
Swanbourne	17.4	16.4	14.7	16.2	16.8	17.3	15.8	17.2	17.0	14.5	12.4	17.4	19.8	21.8	18.7	18.9	19.5	19.6	19.2	17.2	18.6	17.5	19.0	21.1	18.6	20.2	21.0	19.9	20.0	20.3	20.2

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

Details Extremes Records Summaries Important notes the top

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Daily minimum temperature
Central Coast (09)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Bickley	6.7	7.9	4.9	3.9	4.3	5.6	4.8	6.3	5.8	6.2	7.4	7.9	6.9	7.8	10.6	8.9	5.8	5.2	8.5	8.9	8.0	8.6	8.6	9.3	10.7	11.0	8.7	10.7	10.0	11.1	12.3
Champion Lakes	9.0	10.2	6.7	3.8	5.5	5.2	6.5	8.0	8.3	5.6	10.5	10.8	10.4	9.1	12.1	11.2	8.5	9.0	10.7	11.0	9.5	8.8	9.1	11.3	13.9	13.1	9.8	13.7	14.0	13.4	14.7
Garden Island HSF	13.1	12.4	9.3	7.4	7.5	9.7	8.5	10.3	9.9	8.7	10.3	10.7	11.1	10.3	13.8	11.5	8.9	9.4	11.3	12.2	12.5	11.6	11.7	13.6	15.3	15.8	12.6	13.5	13.3	14.8	14.7
Gosnells City							5.6	6.7	8.7	4.8		10.6	10.5	8.5	13.2	10.7	8.7	10.5		10.7	8.6		7.5	12.0	10.9	12.6	8.2	11.0	13.6	12.7	14.2
Jandakot Aero	8.3	10.2	4.6	-0.4	0.6	0.2	1.8	3.9	5.4	1.8	10.2	10.4	7.6	4.0	11.7	8.5	5.1	8.2	5.3	10.1	7.4	7.9	6.9	8.5	12.0	10.4	5.7	13.4	14.3	13.9	15.1
Medina Research Centre	11.1	11.4	6.2	1.3	2.4	7.5	5.0	5.5	7.7	4.5	10.0	10.3	9.3	7.9	13.6	10.1	6.4	7.1	5.5	11.8	11.4	9.9	8.5	11.5	13.2	12.9	9.2	12.5	13.0
Pearce RAAF	7.8	9.1	6.8	0.7	4.2	2.2	4.1	6.6	8.2	5.3	10.3	10.6	9.5	8.4	12.4	8.8	9.4	8.1	10.8	10.4	8.7	9.0	7.6	12.1	13.7	11.3	7.9			13.2	14.1
Perth Airport	8.1	9.1	5.7	0.2	1.8	1.5	2.7	4.4	8.2	2.8	10.1	10.6	9.7	8.2	11.3	9.5	8.0	9.1	10.5	10.7	8.7	7.6	8.2	11.4	13.2	11.3	8.0	14.2	13.8	12.9	13.7
Perth Metro	9.3	9.9	6.6	1.3	1.8	2.6	3.4	4.9	6.3	3.4	10.2	9.8	8.9	6.2	11.5	10.4	7.3	7.4	9.1	10.3	8.3	8.0	7.8	10.7	12.4	11.4	9.0	13.8	14.2	13.1	15.4
Rottnest Island	11.5	12.1	9.2	9.9	9.7	11.6	9.6	11.3	9.7	10.8	10.3	11.0	12.2	13.6	15.6	12.3	12.0	11.7	12.1	12.6	12.2	12.6	13.7	14.2	16.3	14.6	15.0	11.8	13.2	14.8	15.1
Swanbourne	11.1	11.8	7.5	4.7	5.2	6.3	5.9	6.8	7.5	6.0	9.8	10.1	9.6	9.2	12.8	10.7	8.1	7.0	9.6	11.1	10.0	9.3	9.9	11.5	14.0	14.8	10.4	13.4	14.1	14.3	15.1

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

Details Extremes Records Summaries Important notes the top

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Daily rainfall
Central Coast (09)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Bickley	36.4	10.8	5.0	0.2	-	0.2	-	-	-	-	15.6	4.8	0.2	0.2	5.6	16.8	-	-	-	2.8	6.4	12.0	13.8	0.2	0.2	4.0	-	41.4	28.0	28.0	37.4
Champion Lakes	19.8	6.4	8.2	-	-	-	-	-	-	-	6.6	1.6	-	-	0.4	15.2	-	-	-	3.6	5.4	2.8	9.6	-	-	-	-	22.4	14.6	19.4	7.6
Garden Island HSF	23.0	6.2	17.6	-	0.2	-	-	-	-	-	2.8	3.0	0.2	0.2	1.4	12.0	-	-	-	4.4	26.0	6.0	12.0	0.2	-	9.8	0.2	10.8	10.0	6.6	23.0
Gosnells City	18.4	9.0	7.4	0.2	-	-	-	-	»»	»»	»»	7.8	0.2	-	0.8	15.0	-	-	»»	2.8	4.4	»»	12.4	0.1	0.2	1.6	-	17.2	7.5	9.6	22.4
Jandakot Aero	27.2	10.0	8.6	-	0.2	-	-	-	-	-	7.4	3.2	-	-	0.6	9.4	-	-	-	5.2	6.8	3.2	11.4	-	0.2	1.8	-	30.4	11.2	26.0	18.2
Jarrahdale	39.0	5.2	3.6	-	0.2	0.2	0.2	-	0.2	-	9.6	2.4	0.2	0.2	4.2	25.8	0.4	-	0.2	2.4	17.4	4.0	6.0	2.2	0.2	6.8	0.2	14.0	»»	»»	77.4
Medina Research Centre	18.8	9.3	7.9	-	-	-	-	-	-	-	4.2	3.8	-	-	2.4	9.0	-	-	-	5.0	20.4	8.4	6.6	0.3	0.1	3.0	-	17.0	15.4
Mundaring	32.0	20.8	3.4	0.4	0.2	0.2	0.2				11.6	4.0	0.4	0.2	3.2	30.2	0.2	0.2	0.4	4.6	6.8	12.0	12.4	0.8	0.4	6.0	0.2	18.0	34.0	31.6	13.8
Pearce RAAF	13.6	11.6	5.6	-	-	-	-	-	-	-	6.0	6.4	-	»»	2.2	18.6	-	-	-	0.6	8.2	3.2	20.2	-	-	1.2	-			17.0	6.0
Perth Airport	21.4	13.6	3.6	-	-	-	-	-	-	-	7.2	3.4	-	-	4.0	10.8	-	-	-	0.8	4.6	5.6	9.4	-	0.4	1.4	-	21.6	12.6	15.0	24.8
Perth Metro	26.8	9.8	5.4	0.2	-	-	-	-	-	-	6.0	4.8	-	-	4.8	13.4	-	-	-	0.2	4.2	10.6	12.4	-	0.2	1.2	-	14.6	12.4	8.8	25.2
Roleystone	25.8	10.0						0.2			9.6	2.0	0.2		1.0	18.0				2.2	5.0	4.0	13.4	0.4	0.2	3.4		40.6	20.8	22.2	38.8
Rottnest Island	22.0	5.8	10.6	3.6	-	-	-	-	-	-	1.8	3.8	-	-	4.4	4.6	-	-	-	2.8	66.8	5.6	5.4	1.8	-	3.8	0.2	22.2	3.4	3.8	9.2
Serpentine	35.4	5.0	3.2	-	-	-	-	-	-	-	6.6	4.8	-	-	1.4	10.0	0.2	-	-	2.6	13.6	4.8	6.0	0.2	-	5.8	-	14.0	12.8	20.0	31.6
Swanbourne	26.8	4.4	6.0	0.2	0.2	-	0.2	-	-	-	3.4	5.2	-	0.2	0.2	13.6	-	-	-	15.4	5.6	10.2	13.2	-	0.2	1.6	-	15.6	8.6	8.6	15.8

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).
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Details Extremes Records Summaries Important notes the top

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