Perth in January 2015: Thunderstorms ends dry spell

Rainfall in January 2015 was mostly below average across the Perth metropolitan area with most sites recording no rainfall until the last few days of the month. However, thunderstorms on the 29th brought an end to the dry spell. The highest monthly total was 21.3 mm at Roleystone on 3 rain days (7th, 29th, 30th), whilst Perth Airport recorded a mere 0.2 mm for January, whilch is the driest January for five years at Perth Airport, since 2010, when nil rainfall was recorded. A spell of 61 rainless days (29 November 2014 - 29 January 2015) at Perth Metro, was the equal ninth longest dry spell at Perth Metro since records commenced in 1876.

Mean maximum temperatures for January were 1 °C to 2 °C above average for most sites, with means ranging from the high-twenties on the offshore islands, to the low-thirties on the coastal plain and in the hills, and to the mid-thirties in the inland northeast suburbs. A mean maximum temperature of 33.0 °C at Perth Metro was the sixth warmest January since records commenced in 1897.

For most coastal plain sites, days were mainly warm to hot, with one or two very hot days in the first week of January and in the last week of the month. The hottest day across the Perth area was the 5th with daily maxima in the low- to mid-forties at coastal plain sites. A daily maximum temperature of 45.4 °C at Pearce RAAF on the 5th was the highest temperature of the month in Perth, and the equal fifth-highest temperature in January at Pearce RAAF in 53 years of record. Perth Metro recorded a daily maximum temperature of 44.4 °C on the 5th, the third-highest January temperature in 119 years of record, and the highest for 24 years since 31 January 1991 when the record high temperature of 45.8 °C was recorded. Most coastal plain sites experienced a hot spell from the 26th to 28th with daily maximum temperatures at or above 35 °C. The mildest day was the 2nd with daily maxima in the mid- to high-twenties, and the maximum of 22.4 °C at Garden Island was the lowest maximum temperature of the month in Perth.

Mean minimum temperatures were near average across the Perth region in January. Most nights were cool to mild with minima in the mid-to-high teens, interspersed with a few warm nights with minima in the low-twenties on the 5th and 6th, 21st and 22nd, and 27th to 30th. The warmest night was the 28th at most sites, and a minimum temperature of 27.5 °C at Gosnells City on the 28th was the highest minimum of the month in Perth. The lowest temperature of the month was 10.4 °C at Pearce RAAF on the 2nd. Perth Metro recorded a mean minimum temperature of 18.2 °C, close to the mean of 18.1 °C, but the mildest January for eight years, since 2007, when a mean minimum of 16.6 °C was recorded.

  • 61 days without rain at Perth Metro ended on the 29th
  • The third-highest temperature in January on record at Perth Metro on the 5th
  • Significant bushfires occurred in northern and southern Perth suburbs
  • Thunderstorms on the 29th caused approximately 30,000 homes to lose power

Further information

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Extremes in January 2015
Hottest day 45.4 °C at Pearce RAAF on the 5th
Warmest days on average 35.4 °C at Pearce RAAF
Coolest days on average 27.7 °C at Rottnest Island
31.9 °C at Swanbourne
Coldest day 22.4 °C at Garden Island HSF on the 2nd
25.0 °C at Medina Research Centre on the 2nd
Coldest night 10.4 °C at Pearce RAAF on the 2nd
Coolest nights on average 16.1 °C at Bickley
Warmest nights on average 19.1 °C at Rottnest Island
19.0 °C at Gosnells City
Warmest night 27.5 °C at Gosnells City on the 28th
Warmest on average overall 26.5 °C at Gosnells City
Coolest on average overall 23.4 °C at Rottnest Island
24.1 °C at Bickley
Wettest overall 21.3 mm at Roleystone
Wettest day 13.4 mm at Perth Metro on the 30th
Strongest wind gust 76 km/h at Perth Airport on the 10th


Summary statistics for January 2015
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
January
2015
Diff
from
average
Highest for
January
2015
Mean for
January
2015
Diff
from
average
Lowest for
January
2015
Total for
January
2015
Average
for
January
Rank of
January
2015
Fraction of
January
average
Bickley 32.1 +1.5 41.3 5th 16.1 +0.7 11.7 8th 1.4 17.3 average 8%
Garden Island HSF 28.5 +1.1 39.4 5th 19.0 0.0 15.4 3rd 0 9.4 v low 0%
Gosnells City 33.9 +0.7 43.8 5th 19.0 +0.4 14.0 26th 8.8 11.6 high 76%
Jandakot Aero 32.9 +1.5 43.7 5th 17.0 +0.2 13.2 20th 6.4 13.8 average 46%
Medina Research Centre 32.2 +1.5 44.1 5th 17.2 +0.1 12.0 3rd 3.2 11.5 average 28%
Pearce RAAF 35.4 +1.9 45.4 5th 16.8 -0.2 10.4 2nd 1.2 7.6 average 16%
Perth Airport 33.8 +2.1 44.2 5th 17.7 +0.7 13.7 12th 0.2 9.4 low 2%
Perth Metro 33.0 +1.9 44.4 5th 18.2 +0.1 15.2 9th 18.6 9.6 high 194%
Rottnest Island 27.7 +1.2 39.4 5th 19.1 0.0 15.8 9th 0.4 7.6 average 5%
Swanbourne 31.9 +2.1 43.2 5th 18.3 +0.1 14.2 3rd 1.2 14.6 average 8%

Daily maximum temperatures for January 2015
12345678910111213141516171819202122232425262728293031
Bickley29.825.729.235.741.334.931.328.526.327.430.033.335.029.630.431.836.129.727.339.236.730.931.030.530.033.737.538.234.131.528.0
Garden Island HSF23.922.423.933.039.423.928.630.029.031.228.131.426.524.826.527.335.025.124.926.926.822.822.822.927.330.336.433.429.538.031.7
Gosnells City30.727.431.137.843.835.034.032.030.030.932.535.436.430.531.332.537.930.928.240.236.931.732.531.933.536.938.839.036.035.531.2
Jandakot Aero29.326.529.736.343.732.934.132.330.130.731.334.435.029.130.330.037.329.626.537.435.329.730.530.233.636.839.737.434.036.231.5
Medina Research Centre27.025.030.036.344.129.833.732.030.031.031.235.534.128.129.529.436.829.026.536.033.528.527.828.234.037.239.336.433.6
Pearce RAAF32.728.332.538.545.438.235.132.330.130.734.237.038.333.432.935.039.933.331.442.139.729.634.033.633.937.240.842.338.735.731.9
Perth Airport29.427.931.036.844.235.634.531.929.830.332.436.036.430.231.132.238.130.328.239.537.430.631.330.633.236.739.838.737.835.031.4
Perth Metro28.526.329.534.744.434.634.232.330.030.632.035.835.529.730.030.338.029.527.638.935.829.030.429.633.337.140.036.833.934.731.0
Rottnest Island23.923.723.830.739.424.426.526.926.829.127.131.127.025.325.325.432.724.225.129.427.723.724.423.726.028.435.732.826.232.830.2
Swanbourne26.625.530.234.843.229.634.633.431.132.431.134.233.026.930.228.238.426.826.430.834.227.328.427.932.936.638.933.929.838.933.1
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 January 2015
12345678910111213141516171819202122232425262728293031
Bickley13.313.912.112.919.222.817.211.711.812.512.515.218.016.415.114.316.018.716.215.223.118.314.513.313.312.717.522.421.720.615.5
Garden Island HSF17.417.915.417.021.420.119.315.716.016.617.318.019.419.419.218.119.821.819.616.822.221.118.116.317.216.723.124.522.322.720.1
Gosnells City17.814.215.817.524.121.019.515.515.516.717.019.018.818.019.018.619.420.218.916.720.922.618.616.917.014.022.227.521.923.719.8
Jandakot Aero16.614.413.815.322.519.518.315.014.615.916.413.814.013.616.817.613.716.916.213.219.321.216.814.016.316.122.022.321.720.719.3
Medina Research Centre15.515.212.016.522.920.618.515.115.014.516.014.114.315.616.816.918.016.816.014.518.521.015.714.016.516.522.124.922.119.4
Pearce RAAF17.110.413.513.023.019.318.715.314.915.916.913.012.216.116.815.812.717.416.112.519.722.816.312.417.016.224.022.218.920.419.5
Perth Airport17.214.615.715.521.519.919.915.315.116.016.413.713.917.217.818.414.318.219.114.318.622.218.315.617.016.221.922.422.021.619.1
Perth Metro17.415.515.816.223.221.019.915.615.216.216.615.215.317.018.618.317.618.719.116.119.822.615.916.417.216.721.222.423.020.419.5
Rottnest Island17.617.916.017.921.019.819.116.115.816.717.519.019.720.019.319.220.020.518.518.921.920.619.217.317.617.121.422.920.921.920.4
Swanbourne16.415.514.216.522.720.118.615.714.915.916.915.918.818.217.617.218.120.018.616.821.021.616.315.117.116.622.225.821.921.620.1
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 January 2015
12345678910111213141516171819202122232425262728293031
Bickley - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1.4 -
Garden Island HSF - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Gosnells City - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8.6 0.2 -
Jandakot Aero - - - - - - - - - - - - - - - - - - - - - - - - - - - - 6.4 - -
Jarrahdale - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4.2 0.2 -
Medina Research Centre - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3.0 0.2
Mundaring - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1.0 9.2
Pearce RAAF - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1.2 -
Perth Airport - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.2 -
Perth Metro - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5.2 13.4 -
Roleystone - - - - - - 2.2 - - - - - - - - - - - - - - - - - - - - - 11.2 7.9
Rottnest Island - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.4 - -
Serpentine - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1.6 - -
Swanbourne - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.6 0.6 -
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

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.

A Climate Summary is generally published on the first working day of each month.

This statement has been prepared based on information available at 9 am on Monday 2 February 2015. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

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.

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 used for temperature area averages.

Further information

Media
(03) 9669 4057
Enquiries