Perth in May 2017: Warm and dry start

May comprised a warm and dry start, a wet spell in the second half of the month, and a mild and dry end. Rainfall was mostly below average in the Perth metropolitan area whilst both mean maximum and minimum temperatures were higher than normal for most sites.

Below average rainfall for most sites

  • Monthly rainfall was mostly in the 40 to 70 mm range across the metropolitan area, 90 to 100 mm in the hills
  • Perth Metro recorded 70.8 mm rain on 12 rain days in May, its driest May in five years, with 49.0 mm recorded in May 2012
  • May saw a dry start and finish, with a wet spell in the second half of the month and 6 to 8 consecutive rain days
  • Six consecutive rain days from the 19th to 24th at Perth Metro was its longest such wet spell for nine months, since 7 to 12 August 2016
  • Wettest day was the 21st for most sites with the highest daily rainfall in the Perth area of 32.8 mm at Bickley

Mostly above average daytime and overnight temperatures

  • Mean maximum temperatures were within 0.5 °C of average for most sites, though a few sites on the coastal plain were 1°C to 2 °C above average
  • Perth Metro's mean maximum temperature was 22.7 °C, its warmest May for five years, since a mean maximum of 23.1 °C was recorded in May 2012
  • A warm start to May peaked on the 7th, with daily maximum temperatures over 30 °C for most coastal plain sites
  • A daily maximum of 31.8 °C at Perth Metro on the 7th was its warmest day in May for 14 years, since a daily maximum of 32.7 °C on 1 May 2003
  • Mean minimum temperatures were within 0.5 °C of average for most sites, though a few coastal plain sites recorded means between 0.5 °C and 1.5 °C above average
  • Perth Metro's mean minimum temperature was 11.0 °C, its mildest May for three years, since a mean minimum of 12.4 °C was recorded in May 2014.
  • Mild nights with daily minima in the mid-to-high teens were observed early in the month (3rd to 9th)
  • The coldest night for most sites was the 28th with overnight temperatures close to 5 °C on the coastal plain

Further information

Media
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Extremes in May 2017
Hottest day 32.4 °C at Pearce RAAF on the 7th
Warmest days on average 23.7 °C at Pearce RAAF
Coolest days on average 19.5 °C at Bickley
Coldest day 12.8 °C at Bickley on the 20th
Coldest night 3.8 °C at Pearce RAAF on the 28th
Coolest nights on average 10.2 °C at Jandakot Aero
Warmest nights on average 15.2 °C at Rottnest Island
13.2 °C at Gosnells City
Warmest night 19.0 °C at Garden Island HSF on the 9th
18.0 °C at Gosnells City on the 9th
Warmest on average overall 18.2 °C at Rottnest Island
18.1 °C at Gosnells City
Coolest on average overall 14.9 °C at Bickley
Wettest overall 106.8 mm at Karragullen North
Driest overall 41.2 mm at Pearce RAAF
Wettest day 32.8 mm at Bickley on the 21st
Strongest wind gust 85 km/h at Rottnest Island on the 21st




Summary statistics for May 2017
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
May
2017
Diff
from
average
Highest for
May
2017
Mean for
May
2017
Diff
from
average
Lowest for
May
2017
Total for
May
2017
Average
for
May
Rank of
May
2017
Fraction of
May
average
Bickley 19.5 +0.3 27.2 7th 10.3 +0.1 6.2 29th 97.0 131.5 average 74%
Garden Island HSF 21.3 0.0 27.2 3rd 14.1 +0.2 10.2 28th 58.8 77.4 low 76%
Gosnells City 23.0 +0.4 30.5 7th 13.2 +1.5 9.5 25th 68.6 104.0 low 66%
Jandakot Aero 22.4 +0.4 29.7 7th 10.2 +0.9 4.1 28th 73.8 107.2 average 69%
Medina Research Centre 23.1 +1.1 30.1 7th 10.6 +0.1 5.6 29th 66.1 98.2 low 67%
Millendon (Swan Valley) 23.5   31.4 7th 10.3   4.5 28th 55.2
Pearce RAAF 23.7 +1.8 32.4 7th 10.3 -0.4 3.8 28th 41.2 84.3 low 49%
Perth Airport 22.9 +1.2 30.9 7th 11.1 +0.7 4.7 28th 53.6 98.8 low 54%
Perth Metro 22.7 +0.5 30.8 7th 11.0 +0.5 4.9 28th 70.8 116.9 low 61%
Rottnest Island 21.3 +0.2 27.2 7th 15.2 0.0 12.2 28th 56.0 74.9 average 75%
Swanbourne 22.0 -0.2 28.0 7th 12.7 +0.1 7.2 28th 71.0 91.6 low 78%
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 May 2017
12345678910111213141516171819202122232425262728293031
Bickley21.523.826.721.721.223.327.225.416.918.819.418.220.422.416.418.616.921.519.012.813.415.415.418.419.016.315.416.017.921.623.2
Garden Island HSF21.725.627.223.822.022.726.023.919.820.119.421.121.623.419.719.721.422.922.318.317.719.118.921.321.418.018.018.120.222.623.0
Gosnells City24.527.230.524.524.526.630.527.021.221.722.324.025.025.520.122.021.026.023.516.817.319.619.522.022.919.219.020.122.025.4
Jandakot Aero23.626.429.124.623.626.029.726.020.921.522.122.122.824.619.921.320.824.923.017.217.619.419.021.221.919.218.219.020.924.124.2
Karnet21.424.122.021.023.417.818.020.522.316.618.713.115.517.618.519.516.015.916.518.222.6
Medina Research Centre28.229.426.824.026.030.125.420.822.123.025.520.022.121.725.223.517.517.219.720.123.423.619.319.220.021.725.125.7
Millendon (Swan Valley)27.130.424.924.726.931.429.721.221.622.223.626.421.122.520.826.224.116.518.320.221.922.820.018.819.421.925.727.0
Pearce RAAF25.127.830.925.425.227.432.430.221.022.423.422.423.926.021.922.421.026.624.417.019.119.918.122.423.420.719.819.622.128.0
Perth Airport24.726.830.524.624.326.830.928.221.221.722.622.623.325.920.921.820.225.622.217.017.719.217.821.222.519.918.519.521.425.425.7
Perth Metro24.126.429.224.224.326.330.826.420.721.622.122.522.925.020.721.520.425.922.916.918.219.917.921.422.419.418.819.421.624.925.8
Rottnest Island21.225.125.923.822.121.727.223.620.119.719.720.922.423.719.819.421.723.422.617.918.319.318.921.621.319.816.717.718.421.823.1
Swanbourne23.226.527.024.722.525.428.024.420.121.720.322.422.423.620.420.621.323.722.717.918.119.317.621.222.019.618.119.120.623.523.6
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 May 2017
12345678910111213141516171819202122232425262728293031
Bickley9.68.212.015.514.411.711.315.314.48.59.58.68.511.513.011.69.78.313.18.010.07.29.611.29.011.86.36.56.27.710.2
Garden Island HSF14.713.416.417.417.814.614.414.219.011.812.811.513.414.516.015.614.114.917.812.613.511.313.115.512.816.011.610.210.613.212.7
Gosnells City13.416.716.016.814.915.913.918.09.912.012.111.013.816.215.112.013.816.611.612.910.113.014.59.512.09.59.511.014.010.0
Jandakot Aero10.07.911.113.714.711.910.611.416.27.17.77.87.011.215.414.19.48.415.110.212.28.711.812.96.010.44.94.15.911.55.9
Karnet11.09.713.013.112.512.16.99.011.413.010.910.310.55.48.910.16.010.66.05.59.07.2
Medina Research Centre11.410.714.415.28.07.011.216.27.710.69.67.914.410.511.415.911.512.59.011.911.67.813.77.05.95.611.26.9
Millendon (Swan Valley)17.711.215.412.114.09.716.05.68.78.46.111.713.611.58.410.711.910.212.06.511.010.66.48.87.34.58.812.47.1
Pearce RAAF10.913.417.010.415.79.511.210.414.85.38.19.76.712.013.212.98.211.812.111.512.26.510.710.56.59.46.23.87.612.2
Perth Airport13.811.615.413.115.212.412.512.916.96.29.110.19.511.515.514.49.412.313.99.811.87.912.111.68.39.77.14.77.611.47.7
Perth Metro12.110.413.014.216.012.211.713.317.48.610.08.68.011.715.714.510.19.415.410.912.28.511.512.57.410.07.64.95.89.37.7
Rottnest Island15.114.416.918.417.616.517.118.618.615.014.313.014.017.415.915.215.016.417.012.512.712.914.915.815.015.712.712.212.314.114.8
Swanbourne14.312.316.016.916.812.714.316.017.811.411.89.810.813.315.914.911.912.516.411.112.69.111.613.810.213.79.17.28.011.810.8
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 May 2017
12345678910111213141516171819202122232425262728293031
Anketell - - - - 15.2 - - - 2.4 - - - - - 7.4 9.0 - - 11.6 6.0 14.4 9.8 4.6 1.8 - 2.2 - - - - -
Bickley - - - 0.2 8.8 0.2 - - 3.2 - -
- - 6.2 18.8 - 0.2 3.0 8.0 32.8 8.4 4.2 1.0 0.2 1.6 - 0.2 - - -
Bungendore - - - - 12.0 0.2 - - 4.4 - 0.2 - - 0.2 10.8 10.0 0.4 - 6.0 8.0 27.2 8.0 5.2 1.4 0.2 3.2 0.4 0.2 0.2 - -
Chidlow - - - - 6.8 - - - 0.8 - - - - - 8.0 - - 4.2 3.6 26.6 5.0 - 0.6




Garden Island HSF - - - - 14.2 - - - 1.0 - - - - - 3.0 8.2 - - 8.4 0.6 8.8 6.6 5.8 0.4 - 1.8 - - - - -
Gidgegannup - - - - 10.6 0.2 - - 3.2 0.8 - - - - 9.4 13.0 - - 2.6 11.4 23.2 8.6 2.4 7.2 0.2 1.2 0.2 - - - -
Gosnells City - - - - 11.2 - - - 1.4 - - - - - 5.2 5.0 - - 4.0 3.6 21.0 10.2 4.9 0.1 - 2.0 - - - - -
Jandakot Aero - - - - 12.2 - - - 0.8 - - - - - 5.6 5.6 0.2 - 16.8 3.4 16.6 6.2 4.0 1.0 - 1.2 0.2 - - - -
Jarrahdale - 0.2 - - 10.4 0.2 0.2 0.2 6.8 - 0.2 0.2 - - 6.0 11.0 0.2 0.2 7.4 3.2 20.8 8.4 3.0 0.4 0.2 5.2 0.2 0.2 0.2 - 0.4
Karnet - - - 8.0 - -

0.2 - - - - 20.4 14.4 0.4 37.6 2.0 4.6 0.4 0.2 4.4 0.2 - 0.2 - -
Karragullen North - - - - 13.8 - - - 2.4 - - - - - 10.8 15.4 - - 14.8 12.8 19.6 7.6 3.8 4.0 0.4 1.4




Maida Vale - - - - 10.8 - - - 3.4 - - - - - 3.2 7.8 - - 2.6 7.6 22.4 4.4 6.0 1.8 0.8 - - -


Medina Research Centre - - - - 10.4 - - - 1.0 - - - 8.2 5.6 - - 4.2 7.6 11.8 6.8 6.0 0.6 0.1 3.8 - - - - -
Midland - - - - 9.8 - - - 1.1 - - - 7.0 - - - 3.0 42.6 1.6 - - 8.2 - - - -
Millendon (Swan Valley)

- -
0.2 - - 0.8 - -
- - 2.0 1.4 - - 8.2 10.8 20.2 7.8 2.6
0.2 0.8 0.2 - - - -
Mount Helena



8.0


1.4




4.8 8.2

3.4 5.8 29.4 7.0 3.4 3.0 1.0





Mundaring - - - - 8.4 0.2 - - 4.0 - - - - - 7.8 9.0 0.2 - 3.6 12.6 25.6 4.4 5.0 3.2 - 3.2 0.4


Pearce RAAF - - - - 0.8 - - - 0.2 0.2 - - - - 4.4 1.8 - - 1.6 2.0 15.0 2.4 2.8 6.4 - 3.6 - - - -
Perth Airport - - - - 7.6 - - - 1.4 0.2 - - - - 3.4 6.0 - - 1.6 7.4 14.2 4.0 3.8 0.2 - 3.8 - - - - -
Perth Metro - - - - 7.8 0.2 - - 2.2 - - - - - 3.0 7.6 - - 1.0 8.2 17.2 16.0 5.2 1.0 - 1.4 - - - - -
Pickering Brook



14.4


7.8





8.6

3.4 14.0 25.8 13.4 3.4 1.8
1.0




Roleystone - - - - 11.5 - - - 1.6 - - - - - 11.4 - - - 15.2 8.9 24.6 2.6 3.0 - - 2.6




Rottnest Island - - - - 7.4 - - - 0.2 - - - - - 2.0 4.8 - - 7.0 4.6 12.6 3.4 7.2 1.2 - 5.6 - - - - -
Serpentine - - - - 13.6 - - - 6.8 - - - - - 8.2 11.4 - - 15.0 2.4 18.4 8.2 2.0 0.4 - 3.8 - - - - -
Swanbourne - - - - 9.6 0.2 - - 2.4 - - - - - 2.2 10.6 - - 2.8 8.0 15.8 10.2 4.4 2.8 0.2 1.6 0.2 - - - -
Wanneroo - - - - 6.0 - - - 1.6 - - - 1.8 2.6 - - 7.6 28.6 5.4 5.8 0.2 6.4 0.1

Werribee - - - - 6.2 - - - - - - - - - 4.6 5.2 - - 2.2 6.4 13.0 5.0 0.8 2.6 0.2 - - 0.2 - - -
Whiteman Park - - - - 10.6 - - - 1.2 - - - - - 3.4 - - - 8.0 9.6 28.6 8.2 3.6 5.0 - 2.0




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 10 am on Thursday 1 June 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