Perth in April 2013: A very warm month

  • Rainfall: near average to below average
  • Maximum temperature: very much above average; warmest on record for several sites
  • Minimum temperature: warmest on record for most sites

Rainfall

Rainfall across the Perth metropolitan area during April 2013 was near average to below average with monthly rainfall totals generally in the 10 to 30 mm range.

A cloudband associated with ex-tropical cyclone Victoria brought mainly light rainfall from the 11th to 14th to the Perth Metropolitan area with daily rainfall totals mostly less than 5 mm. Generally cloudy conditions with some very light showers continued from the 15th to 18th, although rainfall totals were very low over this period. A middle level cloud band produced showers and thunderstorms across Perth during the morning on the 19th, although again, daily rainfall totals were low and mostly less than 4 mm. A weak cold front crossed the southwest WA on the 20th, with light showers affecting Perth while a stronger cold front moved through the Southwest Land Division (SWLD) during the afternoon of the 21st and morning on the 22nd, bringing the heaviest rainfall of the month to the Perth area, with some moderate falls over 12 mm. Another weak cold front moved through southern WA on the 27th with light showers observed on the 27th and 28th.

Perth Metro recorded 21.0 mm on 10 rain days in April 2013. It was the driest April for 2 years since the 19.4 mm on 7 rain days in 2011. Historically, April rainfall extremes range from nil on three occasions (1920, 1977, and 1982) to 153.6 mm in 2008. Last April (2012), Perth Metro recorded 69.2 mm on 7 rain days.

Maximum temperature

Mean maximum temperatures in April 2013 were 2 °C to 3 °C above average across the Perth metropolitan area, with several sites observing their warmest April on record. The very warm month was mainly due to the generally hot conditions experienced during the first 11 days of April 2013, with the remainder of the month observing mostly closer to average maximum temperatures.

Warm to hot days were experienced across the Perth Metro from the 1st to 4th as a trough near the west coast and a strong high pressure system in the Bight directed northeasterly winds over the area, with daily maxima in high twenties to mid-thirties. Cooler days in the mid-to-high twenties were observed on the 5th and 6th as the trough moved inland, before the hot days resumed from the 7th to 11th as the trough redeveloped near the west coast. One of the hottest April days on record across the Perth area was observed on the 8th with numerous sites breaking their highest April temperature record. Daily maxima was in low thirties on the islands grading to mid-thirties in the western suburbs and hills and reaching the high thirties in the northeast. In addition to breaking its hottest April temperature record on the 8th with a maximum of 35.1 °C, Bickley also equalled the previous record with 34.0 °C on the 11th. Generally mild conditions were observed for the remainder of the month, with the coolest days for April 2013 observed on the 20th and 21st due to cold fronts.

Perth Metro's mean daily maximum temperature in April 2013 was 28.5 °C which was the warmest April since records commenced in 1897, breaking the previous record of 28.2 °C set in 1978 and 1999. Perth Metro recorded four days with a maximum temperature of 36 ° or higher during April 2013, breaking the previous record of one day of 36 °C which has during five other Aprils (1937, 1971, 1978, 2001 and 2007).Interestingly, the mean maximum temperature in April 2013 of 28.3 °C was warmer than 28.0 °C observed in March. This peculiarity of a warmer April than March also occurred in 1924, 1927 and 1999.

Perth Metro's mean daily maximum temperature for the year to date (January to April) was 30.6 °C, which was the equal 3rd hottest start to the year on record, equal with the first four months of 2012.

Minimum temperature

Mean minimum temperatures in April 2013 were very much above average, with some sites more than 3 °C above their April normal. Most of sites recorded their warmest April on record, with mean minima were ranging from mid-teens in the plains and hills to the high teens near the coast and on the islands.

Generally mild to warm nights were experienced from the beginning of the month through to the 19th, with minima generally in mid-to-high teens. Particularly warm conditions were observed at most sites from the 11th through to the 16th, mainly due to middle level cloud, with temperatures remaining in the high teens to low twenties. Bickley broke its previous warmest April minimum temperature of 19.6 °C on three consecutive nights from the 9th to 11th; while Pearce RAAF recorded a daily minimum of 23.0°C on the 3rd which was the highest overnight temperature of the month for the Perth area. Cool nights were recorded on the 23rd, 24th and 29th in the wake of cold fronts, with a number of sites registering overnight temperatures less than 10 °C.

Perth Metro's mean daily minimum temperature in April was 16.7 °C, which was the second warmest April since records commenced in 1897. The warmest April was in 1978 with a mean maximum temperature of 17.3 °C.

As with the maximum temperatures, the mean minimum temperature during April 2013 of 16.7 °C was warmer than the mean minimum temperature of 16.1 °C observed during March, the first occasion since 1962 that this has occurred. Nights warmer in April than March also occurred in 1900, 1918 and 1962.

Sunshine

Perth Metro's mean daily sunshine hours for April was 6.9 hours, which was below the average and the least sunniest April for 32 years since the 6.7 hours in 1981. The average sunshine hours for April is 8.3 hours.

Further information

Media
(03) 9669 4057
Enquiries

Extremes in April 2013
Hottest day 39.4 °C at Pearce RAAF on the 8th
Warmest days on average 29.4 °C at Pearce RAAF
Coolest days on average 25.6 °C at Rottnest Island
26.1 °C at Bickley
Coldest day 18.8 °C at Bickley on the 21st
Coldest night 8.7 °C at Jandakot Aero on the 23rd
Coolest nights on average 15.3 °C at Jandakot Aero
Warmest nights on average 19.3 °C at Rottnest Island
17.8 °C at Champion Lakes
Warmest night 23.0 °C at Pearce RAAF on the 3rd
Wettest overall 27.4 mm at Medina Research Centre
Wettest day 13.6 mm at Gosnells City on the 22nd
Highest wind gust 63 km/h at Bickley on the 7th

Record highest April temperature
Highest temperature
in April 2013 (°C)
Previous warmest
for April
Years of
record
Average for
April
Perth Airport 37.7 on the 8th = 37.7 on the 2nd in 1972 69 25.5
Pearce RAAF 39.4 on the 8th 38.6 on the 4th in 1972 56 26.3
Medina Research Centre 38.1 on the 8th 36.5 on the 16th in 2011 27 25.6
Jandakot Aero 37.0 on the 8th 36.0 on the 16th in 2011 23 25.7
Bickley 35.1 on the 8th 34.0 on the 4th in 2001 20 23.5
Gosnells City 38.5 on the 8th 36.8 on the 4th in 2001 20 26.3
Garden Island HSF 35.7 on the 8th 34.1 on the 12th in 2009 12 23.8



Record highest April mean daily maximum temperature
Mean daily maximum
temperature
for April 2013 (°C)
Previous warmest
for April
Years of
record
Average for
April
Medina Research Centre 28.4 27.6 in 2011 26 25.6
Gosnells City 28.8 28.6 in 2009 19 26.3
Perth Metro* 28.5 28.2 in 1999, 1987 116 25.8
Swanbourne 27.9 27.8 in 1999 19 25.3



Record highest April daily minimum temperature
Highest daily minimum
temperature
in April 2013 (°C)
Previous warmest
for April
Years of
record
Average for
April
Bickley 20.3 on the 9th 19.6 on the 17th in 2011 20 12.5



Record highest April mean daily minimum temperature
Mean daily minimum
temperature
for April 2013 (°C)
Previous warmest
for April
Years of
record
Average for
April
Perth Airport 16.1 15.2 in 1978 68 12.9
Pearce RAAF 16.3 16.0 in 1978 51 13.3
Rottnest Island 19.3 18.5 in 1999 23 17.2
Jandakot Aero 15.3 14.4 in 1991 22 12.3
Bickley 15.7 13.7 in 1999 19 12.5
Swanbourne 17.7 16.3 in 2011 19 15.1
Garden Island HSF 18.3 17.2 in 2011 11 15.8



Summary statistics for April 2013
Maximum temperatures
for April
(°C)
Minimum temperatures
for April
(°C)
Rainfall
for April
(millimetres)
Mean for
April
2013
Diff
from
average
Highest for
April
2013
Mean for
April
2013
Diff
from
average
Lowest for
April
2013
Total for
April
2013
Average
for
April
Rank of
April
2013
Fraction of
April
average
Bickley 26.1 +2.6 35.1 8th 15.7 +3.2 9.8 29th 16.8 55.4 low 30%
Champion Lakes 27.8   35.8 8th 17.8   11.6 23rd 15.0
Garden Island HSF 25.7 +1.9 35.7 8th 18.3 +2.5 13.6 29th 26.4 43.2 low 61%
Gosnells City 28.8 +2.5 38.5 8th     0.0 29th 21.3 44.1 low 48%
Jandakot Aero 28.0 +2.3 37.0 8th 15.3 +3.0 8.7 23rd 19.2 42.9 average 45%
Medina Research Centre 28.4 +2.8 38.1 8th     12.0 29th 27.4 39.8 average 69%
Pearce RAAF 29.4 +3.1 39.4 8th 16.3 +3.0 9.2 23rd 16.0 34.6 low 46%
Perth Airport 28.7 +3.2 37.7 8th 16.1 +3.2 9.6 23rd 7.6 40.9 low 19%
Perth Metro* 28.5 +2.7 37.3 8th 16.7 +3.1 11.0 23rd 21.0 44.1 average 48%
Rottnest Island 25.6 +1.9 32.6 8th 19.3 +2.1 14.3 29th 16.0 35.5 low 45%
Swanbourne 27.9 +2.6 35.8 8th 17.7 +2.6 12.6 23rd 13.8 38.2 low 36%

Daily maximum temperature
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley29.229.431.333.125.825.428.735.133.932.934.022.624.825.626.624.124.123.225.019.718.819.622.025.224.723.622.822.222.128.0
Champion Lakes31.431.333.634.426.627.631.935.833.134.134.923.727.726.628.026.225.925.126.121.620.922.123.827.228.724.524.523.323.729.2
Garden Island HSF30.230.232.430.724.126.328.935.725.629.630.622.325.624.526.024.525.325.225.520.621.621.822.224.024.022.724.620.921.023.2
Gosnells City32.733.235.336.728.028.532.738.534.936.424.528.027.529.327.427.226.527.022.022.923.624.827.827.426.225.824.724.531.8
Jandakot Aero31.932.234.035.826.528.431.437.032.633.834.923.227.327.128.226.725.725.626.622.022.123.023.827.527.024.824.723.623.729.5
Medina Research Centre32.433.135.034.826.028.932.338.132.032.733.623.027.626.427.826.026.426.627.521.521.722.824.426.423.2
Pearce RAAF32.432.734.928.928.732.339.437.936.637.225.528.429.929.527.527.326.227.823.522.623.324.829.528.627.226.426.026.131.3
Perth Airport31.832.034.336.327.728.931.537.734.536.136.524.527.428.328.326.026.925.627.022.922.223.024.628.427.925.525.324.824.630.2
Perth Metro31.732.034.436.227.328.431.737.333.836.436.224.027.028.528.726.426.625.526.621.922.523.124.128.426.425.125.124.224.330.0
Rottnest Island29.929.432.428.324.824.626.332.626.529.929.222.225.025.725.924.225.124.525.521.121.823.522.226.124.424.124.521.621.326.8
Swanbourne31.332.934.433.626.129.832.535.828.635.134.023.127.727.026.625.925.924.925.623.023.023.724.327.926.324.925.423.924.129.3

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 minimum temperature
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley13.714.516.718.617.315.414.817.220.319.720.019.317.218.618.218.817.015.616.114.210.513.311.312.315.616.413.913.49.812.3
Champion Lakes17.717.620.620.718.716.518.321.117.619.522.822.320.419.719.920.719.917.618.715.213.315.811.615.018.916.813.215.113.715.5
Garden Island HSF16.718.319.018.919.618.817.619.618.719.520.021.320.320.120.221.819.918.419.217.614.916.615.115.418.017.419.915.813.615.6
Gosnells City19.517.919.820.719.017.018.520.316.919.522.320.020.019.920.719.917.018.518.010.00.0
Jandakot Aero14.013.916.117.215.816.217.517.713.216.318.920.419.319.518.520.118.614.417.312.810.515.98.710.414.513.911.211.212.113.0
Medina Research Centre12.617.017.019.516.717.317.017.715.517.418.521.019.719.818.820.119.216.018.217.514.012.0
Pearce RAAF19.016.223.018.116.916.317.719.113.616.821.421.219.519.818.219.018.416.117.514.411.915.09.29.618.415.410.610.213.214.4
Perth Airport16.515.016.818.316.317.118.019.114.417.521.121.419.320.619.719.518.715.117.413.610.414.99.69.916.515.311.711.613.315.1
Perth Metro14.913.016.218.118.218.117.718.215.918.520.021.019.720.820.720.819.716.718.116.013.215.611.011.515.716.313.614.112.214.7
Rottnest Island19.220.121.021.520.219.317.820.120.821.222.221.720.419.721.321.220.419.820.216.816.415.916.117.419.619.719.018.514.316.9
Swanbourne17.416.318.720.620.117.617.519.818.119.122.021.219.720.320.421.219.217.417.916.414.015.912.612.616.618.515.714.712.815.6

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 rainfall
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley - - - - - - - 0.2 - - 0.4 2.0 0.2 - - - - 0.6 0.2 - 12.6 0.2 - - - - 0.4 - -
Champion Lakes - - - - - - - - - - - - 1.8 2.8 - - - - 1.6 - - 8.4 - - - - - 0.4 - -
Garden Island HSF - - - - - - - - - - - - 5.0 8.4 0.2 - - 0.2 - - 1.2 6.0 - - - - - 5.4 - -
Gosnells City - - - - - - - - - - »» 0.2 »» »» »» 0.1 - - 1.1 1.2 1.2 13.6 0.1 - - - - 0.8 - -
Jandakot Aero - - - - - - - - - - - - 2.8 1.0 - - 0.2 - 2.2 - - 12.2 - - - - - 0.8 - -
Jarrahdale - - 0.2 - - - - - - - - - 3.8 2.8 - 0.4 0.4 0.2 - - 0.2 8.2 0.4 - 0.2 - - 1.8 0.2 -
Medina Research Centre - - - - - - - - - - - 0.2 5.0 7.3 0.2 0.1 0.1 - - 7.0 0.1 7.4 - - - - - - -
Pearce RAAF - - - - - - - - - - 0.4 0.4 2.8 1.4 - 0.2 - 1.8 0.2 - - 8.8 - - - - - - - -
Perth Airport - - - - - - - - - - - - 1.8 0.2 - - - - 0.8 0.4 - 4.2 0.2 - - - - - - -
Perth Metro - - - - - - - - - - 0.2 0.4 2.8 - - - - - 3.6 0.4 0.2 12.6 0.4 - - - - 0.2 0.2 -
Roleystone - - - - - - - - - 0.2 - 0.6 2.0 0.4 3.4 2.0 - - 0.4 0.2 - 8.6 0.2 - - - - 1.0
Rottnest Island - - - - 0.2 - - - 0.2 - - 0.2 4.2 4.2 - - 0.2 - - 0.4 0.4 5.8 0.2 - - - - - - -
Serpentine - - - - - - - - - - - - 3.6 1.6 - - - 0.4 - - - 6.0 - - - - - 0.6 - -
Swanbourne - - - - - - - - - - - - 3.8 0.2 - 0.2 - 0.2 1.6 0.4 - 6.0 - - - - - 1.4 - -

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 2 pm on Wednesday 1 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.
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.

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