Perth in April 2017: Very dry, sunny, and warm

It was one of the driest Aprils on record for many sites including Perth Metro and Perth Airport, with little or no measurable rainfall reported during the month. Mean maximum temperatures were above average for most locations away from the coast, while mean minimum temperatures were slightly cooler than normal. It was one of the sunniest Aprils on record in Perth.

Rain-free April for most sites

  • No measurable rainfall for most sites, though showers were observed in the metropolitan area on the afternoon of the 23rd
  • Pearce RAAF, Rottnest Island recorded their first rain-free April, and along with Swanbourne registered their driest April on record
  • Both Perth Metro and Perth Airport recorded zero rainfall for the month and their driest April since1982.
  • Perth Metro had four rain-free Aprils (2017,1982,1977,1920) since 1876; Perth Airport had two rain-free Aprils (2017,1982) since records began in 1945
  • A dry spell of 34 days (28 March-30 April) at Perth Metro was its longest March/April dry spell since 37 days on 1 March-6 April 2011

Warmer daytime temperature for most sites; cooler overnight temperatures

  • Mean maximum temperatures were 1 °C to 2 °C above average for most coastal plain sites; coastal and offshore islands recorded slightly below average mean maxima
  • Mean minimum temperatures were generally 0.5 °C to 1 °C below average across the metropolitan area
  • Perth Metro had five consecutive days with temperatures over 30 °C at the start of April, which was the longest such hot spell in April for three years

Sunniest April on record

  • Perth recorded an averaged 9.4 hours per day sunshine, which equaled the record of 9.4 hours per day in April 2011, with sunshine records dated back to 1898
  • Further information

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    Extremes in April 2017
    Hottest day 33.4 °C at Medina Research Centre on the 2nd
    Warmest days on average 28.3 °C at Pearce RAAF
    Coolest days on average 23.1 °C at Garden Island HSF
    24.8 °C at Bickley
    Coldest day 18.7 °C at Bickley on the 17th
    Coldest night 4.3 °C at Jandakot Aero on the 8th
    Coolest nights on average 11.2 °C at Pearce RAAF
    Warmest nights on average 16.8 °C at Rottnest Island
    14.5 °C at Swanbourne
    Warmest night 19.5 °C at Rottnest Island on the 3rd
    18.9 °C at Gosnells City on the 2nd
    Warmest on average overall 20.0 °C at Perth Metro
    20.0 °C at Rottnest Island
    Coolest on average overall 18.5 °C at Bickley
    Wettest overall 2.2 mm at Jarrahdale
    1.0 mm at Jandakot Aero
    Driest overall 0 mm at Perth Metro & others
    Wettest day 1.0 mm at Jandakot Aero on the 24th
    Strongest wind gust 74 km/h at Rottnest Island on the 6th

    Record lowest April total rainfall
    New record
    (mm)
    Old
    record
    Years of
    record
    Average for
    April
    Pearce RAAF 0.0 0.4 in 1982 63 34.8
    Rottnest Island 0.0 3.8 in 2001 25 34.2
    Swanbourne 0.4 5.6 in 2009 23 39.7

    Lowest April total rainfall for at least 20 years
    Observed
    (mm)
    Most recent
    lower
    Average for
    April
    Perth Metro 0.0 0.0 in 1982 44.0
    Perth Airport 0.0 0.0 in 1982 41.1
    Bickley 0.4 0.0 in 1982 55.6
    Jarrahdale 2.2 0.0 in 1982* 60.6

    * note: there are gaps in the historical record at this site, so it is possible a lower value has gone unreported




    Summary statistics for April 2017
    Maximum temperatures
    (°C)
    Minimum temperatures
    (°C)
    Rainfall
    (millimetres)
    Mean for
    April
    2017
    Diff
    from
    average
    Highest for
    April
    2017
    Mean for
    April
    2017
    Diff
    from
    average
    Lowest for
    April
    2017
    Total for
    April
    2017
    Average
    for
    April
    Rank of
    April
    2017
    Fraction of
    April
    average
    Bickley 24.8 +1.3 29.7 3rd 12.2 -0.5 6.8 8th 0.4 55.6 v low 1%
    Garden Island HSF 23.1 -0.8 30.0 2nd 15.2 -0.9 11.9 8th 0 38.4 v low 0%
    Gosnells City 27.8 +1.4 32.8 3rd     8.9 30th 0 43.2 lowest 0%
    Jandakot Aero 26.8 +1.1 32.0 3rd 11.7 -0.8 4.3 8th 1.0 41.8 v low 2%
    Pearce RAAF 28.3 +1.9 33.1 3rd 11.2 -2.2 5.0 30th 0 34.8 lowest 0%
    Perth Airport 27.5 +1.9 32.6 3rd 12.1 -0.9 6.2 30th 0 40.5 lowest 0%
    Perth Metro 27.0 +1.1 31.8 3rd 12.9 -0.9 8.3 26th 0 44.0 lowest 0%
    Rottnest Island 23.3 -0.5 30.0 2nd 16.8 -0.5 13.0 8th 0 34.2 lowest 0%
    Swanbourne 24.9 -0.5 31.5 2nd 14.5 -0.8 10.4 8th 0.4 39.7 lowest 1%
    Note: Observations for “Perth Metro” are taken from the current site at Mount Lawley (Bureau number 009225).
    Comparisons are made against combined data from the current site (which opened in early 1993) and the previous site at Perth Regional Office (009034), which ran from 1876 to early 1992.

    Daily maximum temperatures for April 2017
    123456789101112131415161718192021222324252627282930
    Bickley27.028.429.728.128.523.620.021.924.426.426.522.424.928.526.623.418.721.323.926.326.825.624.923.821.723.424.524.025.223.1
    Garden Island HSF30.030.023.122.926.720.719.419.925.023.724.821.621.322.123.421.819.821.021.826.424.122.725.521.521.022.522.222.724.921.4
    Gosnells City30.431.532.832.130.525.523.124.629.928.424.828.130.430.127.324.825.829.529.528.928.127.224.826.126.727.027.324.5
    Jandakot Aero30.031.632.030.129.325.322.323.827.129.127.324.226.728.428.426.321.424.225.128.527.828.428.225.924.525.325.825.926.524.5
    Karnet26.628.528.228.527.523.019.521.424.526.526.525.023.623.221.424.020.924.024.525.4
    Medina Research Centre33.033.430.730.830.124.322.528.430.6
    Pearce RAAF30.932.233.131.532.826.523.125.427.330.031.425.428.530.930.227.322.626.127.029.730.230.229.127.225.127.327.726.728.125.6
    Perth Airport30.131.732.631.030.625.223.024.427.329.728.524.828.029.430.126.422.224.425.829.229.628.728.627.024.625.926.326.827.625.2
    Perth Metro30.131.631.830.430.424.422.323.627.430.128.123.826.829.029.325.121.825.025.628.628.328.628.126.024.226.126.326.727.623.9
    Rottnest Island28.530.024.023.026.121.519.720.423.623.625.422.721.923.123.721.819.821.521.825.724.123.223.821.620.922.223.524.024.821.8
    Swanbourne30.231.526.225.328.222.421.122.326.929.125.123.023.724.926.122.920.922.722.927.224.824.227.623.721.824.723.524.325.722.6
    Values are the maximum temperature, usually in the 24 hours from 9 am on the day indicated,
    and typically occurred in the afternoon of that day.
    Temperatures coloured according to 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 Grey outline marks highest
    and lowest for the period

    Daily minimum temperatures for April 2017
    123456789101112131415161718192021222324252627282930
    Bickley11.113.815.312.013.413.710.76.89.410.812.110.213.113.215.113.812.513.912.612.313.914.514.111.39.59.811.210.613.3
    Garden Island HSF16.318.617.016.012.013.914.511.914.214.414.914.315.815.416.917.316.917.715.915.714.217.417.515.613.712.515.213.412.713.8
    Gosnells City16.018.914.216.516.012.814.511.414.115.011.914.616.914.117.314.312.012.214.811.215.512.012.08.9
    Jandakot Aero14.517.211.615.311.59.514.24.39.611.211.49.511.414.713.616.214.214.010.58.610.414.816.414.110.37.810.68.68.66.3
    Karnet12.011.912.011.010.57.510.510.013.28.512.014.113.511.98.89.59.58.4
    Medina Research Centre11.014.410.011.813.87.011.79.5
    Pearce RAAF15.416.011.215.111.011.113.16.67.913.514.27.711.011.911.316.911.49.78.97.710.812.916.913.412.16.612.66.67.25.0
    Perth Airport14.717.111.115.912.610.314.37.99.914.313.27.212.913.511.917.414.511.411.89.111.215.116.714.512.16.512.49.36.86.2
    Perth Metro14.917.412.115.412.313.714.88.711.110.013.110.612.912.814.817.215.415.314.111.212.215.316.514.613.28.312.09.68.78.7
    Rottnest Island16.919.119.516.518.017.914.613.015.115.817.416.416.317.117.818.017.217.917.117.717.817.917.916.214.614.916.916.016.217.5
    Swanbourne15.618.316.515.815.415.914.410.413.513.715.013.013.914.415.417.215.615.514.614.114.216.316.614.612.211.913.512.411.812.1
    Values are the minimum temperature, usually in the 24 hours to 9 am on the day indicated,
    and typically occurred that morning.
    Temperatures coloured according to 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 Grey outline marks highest
    and lowest for the period

    Daily rainfall for April 2017
    123456789101112131415161718192021222324252627282930
    Anketell - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Bickley - - - - - - - - - - - - 0.2 - - - - - - 0.2 - - - - - - -
    - -
    Bungendore - - - - - - - - - - - - 0.2 - - - - - - 0.2 - - - - - - - - - -
    Garden Island HSF - - - - - - - - - - - - - - - -
    - - - - - - - - - - - - -
    Gidgegannup - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Gosnells City - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Jandakot Aero - - - - - - - - - - - - - - - - - - - - - - - 1.0 - - - - - -
    Jarrahdale - - - - - 0.2 - 0.2 - 0.2 - 0.2 - 0.2 - - - - 0.2 0.2 0.2 - - - - 0.2 - 0.2 - 0.2
    Karnet - - - - - - - - - - - - - -
    - - - - - - - - - - - - - - -
    Medina Research Centre - - - - - - - - - - -


















    Midland - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    Pearce RAAF - - - - - - - - - - - - - - - - - - - - -
    - - - - - - - -
    Perth Airport - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Perth Metro - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Rottnest Island - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Serpentine - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Swanbourne - - - - - 0.4 - - - - - - - - - - - - - - - - - - - - - - - -
    Werribee - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    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 shown 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).
    Rainfalls coloured
    according to the amount
    0 1.0 5.0 10.0 15.0 25.0 50.0 100 150 200 300 400 600 millimetres

    Notes

    The Monthly climate summary, generally published on the first working day of each month, lists 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. More extensive discussion of significant weather events, along with later information and data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review.

    This statement has been prepared based on information available at 9 am on Monday 1 May 2017. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

    In some situations, some or all of the rainfall is in the form of hail or snow. In these cases the totals given are for the water equivalent: the depth of liquid water that results from melting any frozen precipitation. There can be significant 'undercatch' of snow in strong winds, meaning the true precipitation can be higher than that reported.

    Averages for individual sites 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.

    Observations for “Perth Metro” are taken from the current site at Mount Lawley (Bureau number 009225).
    Comparisons are made against combined data from the current site (which opened in early 1993) and the previous site at Perth Regional Office (009034), which ran from 1876 to early 1992.

    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.

    Where temperature area averages are mentioned, they are derived from the ACORN-SAT dataset.

    Further information

    Media
    (03) 9669 4057
    Enquiries