Perth in April 2011: A warm and sunny month

  • Rainfall: Below to near average.
  • Maximum temperature: Very much above average.
  • Minimum temperature: Above to very much above average.

Rainfall

Rainfall across the Perth metropolitan area during April 2011 was below average to close to average across the Perth metropolitan area, with a number of sites observing less than 50% of their average April rainfall. Much of the rainfall over the Perth area during April 2011 occurred over the Easter weekend due to cold fronts crossing the southwest of WA. The wettest day for most sites was in the 24 hours to 9am on the 28th, with widespread falls in the 10 to 20 mm range and Roleystone observing the wettest day of the month with 26.0 mm.

Perth Metro recorded 19.4 mm of rainfall on 7 days during April 2011, which is below average. The total rainfall for the four months from January to April 2011 at Perth Metro was also below average, with 50.0 mm recorded on 14 rain days. The average for this period is 85.8 mm on about 15 days, while the total for the same period last year was 65.6 mm on 9 days.

Maximum temperature

Daytime temperatures during April 2011 were very much above average across Perth, with most sites observing mean daily maximum temperatures 2 to 3 °C above normal. Jandakot Aerodrome broke its highest daily maximum temperature record with 36.0 °C on the 16th.

Perth Metro's mean maximum temperature in April 2011 was 27.3°C which is the fifth hottest April on record. The hottest April on record was the 28.2 °C observed in 1978.

Perth Metro has observed its hottest start to the year on record, with a mean maximum temperature of 31.5 °C for the first four months of 2011, breaking the previous record of 31.3 °C set in 1978. This is the result of observing the 7th hottest January, 3rd hottest February, hottest March and 5th hottest April on record. Perth Metro has observed 62 hot days (maximum temperature of 32 °C or more) during the first four months of 2011 (including four in April), breaking the previous record of 53 in 1978. The most number of hot days observed over the whole year at Perth Metro was 66 in 1978 followed by 65 in 2010.

Minimum temperature

Overnight temperatures during April 2011 were also above average across Perth, with most sites observing mean daily maximum temperatures 1 to 2 °C above normal. Swanbourne observed their warmest April on record in terms of overnight temperature.

Perth Metro's mean minimum temperature in April was 14.8 °C, which is above average. Perth Metro has observed its fifth warmest start to the year on record in terms of overnight temperature, with a mean minimum temperature of 18.5 °C. The warmest January to April on record was 19.6 °C in 1978.

Wind and sunshine

No severe wind gusts (wind gust of 90 km/h or more) were observed in the Perth region during April 2011. Pearce RAAF observed an easterly wind gust of 76 km/h at 0806 WST on the 10th, while Rottnest observed a southwesterly wind gust of 76 km/h at 1855 WST on the 27th.

Perth recorded an average daily sunshine of 9.4 hours in April, which is the sunniest April on record. The previous record for April was 9.3 hours per day in 1920, while the average is 8.2 hours per day.

Further information

Media
(03) 9669 4057
Enquiries

Extremes in April 2011
Hottest day 36.6 °C at Gosnells City on the 16th
Warmest days on average 28.3 °C at Gosnells City
28.3 °C at Pearce RAAF
Coolest days on average 25.0 °C at Bickley
Coldest day 17.8 °C at Bickley on the 28th
Coldest night 5.4 °C at Jandakot Aero on the 8th
Coolest nights on average 13.5 °C at Bickley
Warmest nights on average 18.4 °C at Rottnest Island
Warmest night 22.3 °C at Rottnest Island on the 17th
Wettest overall 53.4 mm at Jarrahdale
Wettest day 26.0 mm at Roleystone on the 28th
Highest wind gust 76 km/h at Pearce RAAF on the 10th
76 km/h at Rottnest Island on the 27th

Record highest April temperature
Highest temperature
in April 2011 (°C)
Previous warmest
for April
Years of
record
Average for
April
Jandakot Aero 36.0 on the 16th 35.7 on the 4th in 1991 21 25.6



Record highest April mean daily minimum temperature
Mean daily minimum
temperature
for April 2011 (°C)
Previous warmest
for April
Years of
record
Average for
April
Swanbourne 16.3 16.2 in 1999 17 15.0


Summary statistics for April 2011
Maximum temperatures
for April
(°C)
Minimum temperatures
for April
(°C)
Rainfall
for April
(millimetres)
Mean for
April
2011
Diff
from
average
Highest for
April
2011
Mean for
April
2011
Diff
from
average
Lowest for
April
2011
Total for
April
2011
Average
for
April
Rank of
April
2011
Fraction of
April
average
Bickley 25.0 +1.6 33.2 16th 13.5 +1.1 8.6 8th 34.0 55.7 average 61%
Champion Lakes 26.6   34.2 16th 16.1   10.7 8th 28.2
Garden Island HSF 26.0   33.7 5th 17.2   12.4 29th 20.6 44.5 low 46%
Gosnells City 28.3 +2.1 36.6 16th 15.4 +0.8 9.2 29th 27.8 44.0 average 63%
Jandakot Aero 27.6 +2.0 36.0 16th 13.6 +1.4 5.4 8th 34.2 42.8 average 80%
Medina Research Centre 27.6 +2.1 36.5 16th 14.5 +1.3 7.0 29th 21.7 39.7 average 55%
Pearce RAAF 28.3 +2.0 36.1 16th 15.0 +1.7 7.2 30th 16.4 34.7 low 47%
Perth Airport 27.9 +2.4 36.3 16th 14.2 +1.3 6.5 30th 25.4 41.2 average 62%
Perth Metro* 27.3 +1.7 35.7 16th 14.8 +1.2 7.9 30th 19.4 44.1 low 44%
Rottnest Island 25.5 +1.9 32.0 4th 18.4 +1.3 14.2 9th 13.8 36.5 low 38%
Swanbourne 27.6 +2.5 34.6 5th 16.3 +1.3 10.4 29th 19.8 37.0 low 54%

Daily maximum temperature
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley28.927.729.130.932.630.219.921.123.326.422.021.522.724.428.233.225.222.924.223.226.230.225.822.924.324.618.717.820.420.7
Champion Lakes30.229.730.932.733.630.321.823.025.128.423.923.724.425.830.334.226.324.626.324.928.231.226.124.725.725.322.019.923.022.3
Garden Island HSF32.631.229.132.633.726.922.421.326.328.624.824.822.624.030.533.323.823.421.724.128.130.226.424.725.025.221.520.120.221.2
Gosnells City33.531.533.034.335.832.223.024.526.530.225.525.025.827.031.536.630.726.227.225.832.528.027.028.026.923.021.325.023.5
Jandakot Aero31.930.832.233.735.330.423.123.626.629.725.524.825.926.431.536.026.525.725.926.029.031.128.025.626.226.222.920.523.323.4
Medina Research Centre32.331.231.834.536.422.323.826.229.126.225.224.925.131.636.525.925.225.125.829.531.128.326.927.027.223.021.223.323.0
Pearce RAAF31.230.031.633.936.033.424.124.225.930.125.725.925.727.031.336.128.625.227.526.329.834.330.427.527.828.123.520.923.123.5
Perth Airport31.730.731.933.635.831.023.824.126.430.525.025.525.926.831.436.327.926.427.026.129.332.728.225.726.727.222.320.524.123.6
Perth Metro31.130.331.433.634.730.522.423.526.029.324.824.624.825.830.835.727.226.325.325.628.932.327.225.626.626.122.220.623.123.0
Rottnest Island29.429.130.332.031.926.322.521.124.828.424.824.823.023.829.831.524.322.622.022.926.028.326.025.524.624.821.620.220.421.3
Swanbourne32.631.032.733.734.627.422.624.526.230.525.624.924.927.131.734.527.126.724.926.529.933.227.126.125.625.622.921.123.923.1

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


Daily minimum temperature
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley14.713.415.115.216.619.313.08.68.611.815.314.511.910.511.616.219.615.810.211.412.312.817.419.014.013.214.28.79.09.7
Champion Lakes18.317.519.619.018.416.815.510.712.416.218.517.013.814.415.420.919.918.913.714.615.116.918.120.814.914.317.210.811.112.5
Garden Island HSF19.318.219.820.317.516.515.113.513.417.120.119.717.016.816.120.420.018.113.914.816.518.317.021.618.116.118.415.412.413.5
Gosnells City18.219.820.411.015.018.015.912.613.115.021.019.718.713.915.215.417.516.014.013.416.910.49.29.5
Jandakot Aero17.417.117.815.511.212.615.05.410.016.318.817.89.910.610.719.617.618.513.18.99.716.415.518.913.310.217.410.36.67.2
Medina Research Centre17.916.920.018.613.013.714.49.011.816.619.819.211.912.613.215.517.712.910.313.017.014.120.314.312.317.711.57.09.5
Pearce RAAF18.718.520.021.214.813.015.210.313.316.917.915.814.210.69.221.218.319.313.513.315.618.516.517.912.410.515.210.99.87.2
Perth Airport16.617.215.917.513.313.914.47.511.216.118.417.211.111.510.920.618.119.314.111.411.717.017.718.813.512.015.79.67.46.5
Perth Metro18.117.116.914.813.115.414.79.012.316.619.319.413.312.811.120.518.919.114.011.110.316.717.419.214.312.817.112.98.07.9
Rottnest Island20.119.321.022.121.622.015.615.314.216.819.919.217.717.817.320.522.318.615.816.517.419.220.822.218.519.017.214.314.415.1
Swanbourne18.117.519.319.517.917.914.111.712.616.819.318.914.414.713.221.119.918.213.913.313.317.419.121.115.314.818.414.510.411.3

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) 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
Bickley - - - - - - 0.6 4.4 - - 3.8 0.8 - - - - - - - - - - - - 2.2 - 6.4 15.8 - -
Champion Lakes - - - - - - 2.4 - - - 1.0 - 0.2 0.2 - - - - - - - - - - 0.4 0.2 4.0 19.8 - -
Garden Island HSF - - - - - - 4.2 0.2 - - - 0.2 0.2 - - - - - - - - - - 0.8 3.0 0.2 7.2 3.4 1.0 0.2
Gosnells City - - - - - - 2.0 0.6 - - 3.6 0.6 - - - - - - - - - - - 1.0 - - 9.0 11.0 - -
Jandakot Aero - - - - - - 2.2 0.8 - - 2.8 0.4 - - - - - - - - -
- 4.2 5.0 - 4.0 14.2 0.6 -
Jarrahdale - - - - - - 3.6 4.4 - - 0.8 0.4 - 0.2 0.2 - - - 0.2 - - - - - 9.0 0.2 11.0 23.0 0.2 0.2
Medina Research Centre - - - - - - 3.4 1.1 - - 1.6 1.4 - 0.2 - - - - - - - - - - 1.2 - 4.8 5.4 2.6 -
Mundaring





1.0 0.4

3.8 2.8
0.2

0.4






1.6 0.2 9.2 17.2
0.2
Pearce RAAF - - - - - - 0.4 0.4 - - 2.4 - - - - - - - - - - - - - 0.2 - 1.0 12.0 - -
Perth Airport - - - - - - 1.0 0.2 - - 2.2 0.6 - - - - - - - - - - - 3.0 0.2 - 6.2 12.0 - -
Perth Metro - - - - - - 2.0 0.2 - - 2.2 - - - - - - - - - - - - 0.4 0.8 - 9.6 4.2 - -
Roleystone





1.2 1.4

3.8 1.2 0.2


0.2






3.0
8.8 26.0

Rottnest Island - - - - - 0.2 4.2 - - - 0.4 - - - - - - - - - - - - - 1.0 - 6.6 1.4 - -
Serpentine - - - - - - 2.4 4.6 - - 2.6 0.2 - - - - - 0.2 - - - - - 0.2 6.8 - 6.2 7.6 0.2 -
Swanbourne - - - - - - 3.2 - - - 3.4 0.4 - - - - - - - - - - 0.2 1.0 0.6 - 4.2 6.6 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 11 am on Monday 2 May 2011. 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 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