Perth in January 2013: Warm January nights

  • Rainfall: near average to above average
  • Maximum temperature: near average
  • Minimum temperature: above average

Rainfall

Rainfall across the Perth metropolitan area during January 2013 was near average to above average. Monthly rainfall totals for most sites were between 5 mm and 10 mm, however rainfall totals in the hills were closer to 20 mm.

Light showers with falls generally less than 1 mm were observed in the Perth area in the late evening on the 1st as a tropical low, the remnants of tropical cyclone Mitchell, dissipated off the southwest coast. A trough near the west coast produced showers across the Perth metropolitan area on the 6th, and showers and thunderstorms on the 7th, with falls during the event in the 5 mm to 10 mm range on the coastal plain and 10 mm to 20 mm in the hills. A cloudband associated tropical cyclone Narelle brought rain to the Perth metropolitan area on the afternoon of the 13th and morning of the 14th, though falls were generally less than 2 mm. Light showers were also observed as a weak cold front moved through the Perth region on the afternoon and evening of the 16th with rainfall totals mostly less than 3 mm.

Perth Metro recorded 7.2 mm of rainfall on 5 rain days in January 2013, close to the long-term average of 9.7 mm. The highest daily rainfall at Perth Metro during January 2013 was 4.8 mm on the 7th. It was Perth Metro's driest January for three years, since no measurable rainfall was recorded in January 2010.

Maximum temperature

Mean maximum temperatures in January 2013 across the Perth metropolitan area were near average. Mean maxima were in the high twenties on the offshore islands and in the low thirties on the coastal plain and in the hills.

After a record equalling seven day heatwave to end December, with the hottest day of December occurring at most metropolitan sites on 31 December, January 2013 began with a cooler change and mild to warm days up to the 4th with temperatures in the mid-twenties to low thirties. A relatively hot spell occurred from the 5th to 8th as temperatures were in the mid-to-high thirties at most sites, with the 8th being the hottest day of the month for most sites. Daily maxima over 37 °C were reported across the coastal plain and in the hills, and 41.1 °C at Pearce RAAF was the highest temperature recorded in the Perth metropolitan area in January 2013. A pattern of a mild to warm days interspersed with a hot day or two was observed for the remainder of the month after the 8th, with a hot day for most sites on the 14th, whilst the the lowest maximum temperature at all sites was recorded on the 17th with maxima typically in the mid-twenties.

Perth Metro's mean daily maximum temperature in January was 31.7 °C, which is close to the average of 31.0 °C. Daily maxima at Perth Metro ranged from a very hot 39.1 °C on the 8th to a mild 24.5 °C on the 17th. The mean maximum temperature for summer 2012-13 so far (December 2012 - January 2013) is 31.5 °C, which is the equal third highest mean maximum temperature for the December - January period since records commenced at Perth Metro in 1897.

Minimum temperature

Mean minimum temperatures in January 2013 were above average across the Perth metropolitan area, with mean minima generally in the mid-teens in the hills, the high teens on the coastal plain, and near 20 °C on the offshore islands.

The first two days of January 2013 saw warm overnight conditions for most sites, with minima in the low-to-mid twenties, whilst consecutive warm to hot nights were experienced between the 6th and 9th, and 13th and 16th. The islands recorded their warmest night of the month on the 7th-8th, however the 14th-15th was the hottest night of the month across most of Perth, with daily minima in the mid-to-high twenties. Perth Airport recorded its hottest January night in 69 years of record with a daily minimum temperature of 27.8 °C on the 15th, exceeding its previous record of 27.3 °C set on 21 January 1989. Gosnells City recorded a minimum temperature of 29.0 °C, which was the highest overnight temperature of the month in the Perth area, and the equal highest January minimum at Gosnells City in its 20 years of record. Apart from a relatively warm night on the 26th-27th, mostly mild nights were experienced throughout the second half of January 2012. The coolest mornings of the month were reported on both the 5th when inland sites on the coastal plain recorded minima in the 12 °C to 14 °C range, and the 18th as coastal, offshore islands, and hills sites recorded their lowest temperatures of the month. Minima in the mid-teens were reported at coastal and offshore sites on the 18th, whilst Bickley in the hills recorded the lowest temperature in the Perth Metropolitan area during January of 10.9 °C on the 18th.

Perth Metro's mean daily minimum temperature in January 2013 was 19.3 °C, which was well above the long-term mean of 18.0 °C. Daily minima ranged from a mild 14.0 °C on the 5th to a very warm 27.3 °C on the 15th. It was Perth Metro's third consecutive January with a mean minimum over 19 °C, a mean that had not been achieved at the Mt Lawley site in January in its 17 previous years of monitoring.

Sunshine

The mean daily sunshine hours for January 2013 was 11.2 hours, which is near the average of 11.5 hours.

Further information

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Extremes in January 2013
Hottest day 41.1 °C at Pearce RAAF on the 8th
Warmest days on average 34.0 °C at Pearce RAAF
Coolest days on average 27.0 °C at Rottnest Island
30.3 °C at Bickley
Coldest day 21.7 °C at Garden Island HSF on the 17th
23.6°C at Bickley on the 17th
Coldest night 10.9 °C at Bickley on the 18th
Coolest nights on average 16.4 °C at Bickley
Warmest nights on average 20.0 °C at Garden Island HSF
19.5 °C at Champion Lakes
Warmest night 29.0 °C at Gosnells City on the 15th
Wettest overall 24.6 mm at Jarrahdale
Wettest day 17.4 mm at Jarrahdale on the 7th
Highest wind gust 80 km/h at Rottnest Island on the 17th



Record highest January daily minimum temperature
Highest daily minimum
temperature
in January 2013 (°C)
Previous warmest
for January
Years of
record
Average for
January
Perth Airport 27.8 on the 15th 27.3 on the 21st in 1989 69 17.0
Gosnells City 29.0 on the 15th = 29.0 on the 28th in 2012 20 18.5



Summary statistics for January 2013
Maximum temperatures
for January
(°C)
Minimum temperatures
for January
(°C)
Rainfall
for January
(millimetres)
Mean for
January
2013
Diff
from
average
Highest for
January
2013
Mean for
January
2013
Diff
from
average
Lowest for
January
2013
Total for
January
2013
Average
for
January
Rank of
January
2013
Fraction of
January
average
Bickley 30.3 -0.3 38.2 8th 16.4 +1.1 10.9 18th 17.2 18.0 average 96%
Champion Lakes 31.5   38.8 8th 19.5   14.1 18th 8.2
Garden Island HSF 27.1 -0.2 33.5 14th 20.0 +1.2 15.1 18th 4.6 11.0 average 42%
Gosnells City 33.2 +0.1 39.9 8th         1.2 12.0 average 10%
Jandakot Aero 31.5 +0.2 38.3 8th 18.3 +1.6 12.1 5th 6.4 14.4 high 44%
Pearce RAAF 34.0 +0.5 41.1 8th 18.2 +1.2 12.6 5th 8.8 7.8 high 113%
Perth Airport 32.2 +0.5 39.4 8th 18.5 +1.5 12.7 5th 7.4 9.7 average 76%
Perth Metro 31.7 +0.6 39.1 8th 19.3 +1.3 14.0 5th 7.2 9.7 average 74%
Rottnest Island 27.0 +0.6 33.1 7th 20.0 +0.9 15.6 18th 6.6 7.8 high 84%
Swanbourne 30.7 +1.0 37.6 8th 19.1 +1.0 14.1 18th        

Daily maximum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley31.328.024.824.836.029.332.938.227.226.029.731.025.635.132.624.723.627.030.934.133.134.029.229.131.033.232.829.330.832.4
Champion Lakes29.628.325.526.137.233.437.538.827.426.331.533.628.336.232.225.924.829.632.734.333.635.829.530.132.334.434.431.531.933.1
Garden Island HSF28.925.625.823.627.433.331.731.223.322.924.931.729.333.530.326.621.725.829.325.824.626.123.823.325.828.427.230.125.825.2
Gosnells City32.228.038.535.038.239.928.927.932.035.033.337.834.427.825.830.534.036.235.037.031.230.733.035.532.833.234.3
Jandakot Aero30.827.926.926.035.634.038.238.327.326.529.635.028.336.332.727.324.730.032.833.732.335.329.028.630.434.435.632.631.632.3
Pearce RAAF36.931.429.628.239.834.337.841.129.728.932.335.428.039.036.931.327.230.434.437.835.637.431.731.934.536.736.533.035.535.7
Perth Airport32.028.626.926.137.934.137.739.428.227.430.434.228.537.433.727.626.030.133.835.932.936.129.729.732.135.436.232.432.834.1
Perth Metro30.828.527.325.636.935.337.839.126.426.229.434.928.137.332.627.124.530.233.235.131.535.728.728.430.834.934.532.532.732.3
Rottnest Island28.225.826.024.228.333.033.131.724.324.424.928.827.132.128.725.723.324.927.227.025.426.225.023.925.928.726.827.027.525.3
Swanbourne29.027.427.726.635.934.936.137.626.226.228.435.529.633.430.826.625.229.233.830.828.033.726.727.131.034.633.933.032.830.0

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)12345678910111213141516171819202122232425262728293031
Bickley22.818.315.413.114.523.221.621.818.612.713.116.418.719.024.219.715.010.912.916.915.514.218.113.612.015.016.412.913.815.913.5
Champion Lakes26.021.617.715.916.423.424.025.321.615.916.119.722.321.727.422.919.114.116.720.019.418.218.116.315.918.720.316.617.918.917.4
Garden Island HSF24.421.320.619.018.422.323.324.921.617.817.419.522.123.324.522.519.815.117.217.719.517.821.518.716.518.720.616.918.619.617.4
Gosnells City26.217.023.724.521.615.215.820.022.021.329.021.318.613.815.718.219.016.518.118.817.2
Jandakot Aero25.121.415.817.112.121.323.924.921.712.314.419.521.821.326.522.718.813.516.314.117.117.516.914.115.513.920.116.216.117.316.9
Pearce RAAF24.421.415.515.312.621.323.625.321.614.415.220.321.921.525.321.317.614.516.314.014.418.215.314.216.914.221.017.017.814.017.5
Perth Airport24.321.716.214.212.721.223.425.322.313.016.020.222.121.827.821.019.014.216.513.818.618.017.314.316.113.820.116.517.817.217.1
Perth Metro25.121.618.918.314.022.024.025.222.315.616.720.422.221.727.322.819.115.116.615.419.418.120.017.216.115.420.616.817.816.817.2
Rottnest Island23.020.819.318.319.222.323.224.520.819.418.219.922.022.023.521.618.615.617.620.219.818.220.718.917.319.821.417.719.020.817.9
Swanbourne24.221.119.318.414.721.423.324.321.615.615.919.922.021.124.722.218.914.116.817.518.117.220.016.416.218.220.117.017.118.717.4

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)12345678910111213141516171819202122232425262728293031
Bickley - 0.4 - - - - 11.4 1.0 - - - - - 1.6 - - 2.8 - - - - - - - - - - - - - -
Champion Lakes - - - - - - 5.2 0.2 - - - - - 1.6 0.2 - 1.0 - - - - - - - - - - - - - -
Garden Island HSF - - - - - - 4.4 0.2 - - - - - - - - - - - - - - - - -
- - - - -
Gosnells City - -

- - - - - - - - - - - - 1.2 - - - - - - - - - - - - - -
Jandakot Aero - 0.2 - - - - 3.8 0.2 - - - - - 1.6 - - 0.6 - - - - - - - - - - - - - -
Jarrahdale - 0.6 0.2 - - - 17.4 0.6 - - - - - 2.8 - - 3.0 - - - - - - - - - - - - - -
Pearce RAAF - - - - - - 4.2 - - - - - - 4.4 - - 0.2 - - - - - - - - - - - - - -
Perth Airport - - - - - - 6.6 0.4 - - - - - 0.4 - - - - - - - - - - - - - - - - -
Perth Metro - 0.4 - - - - 4.8 0.2 - - - - - 1.2 - - 0.6 - - - - - - - - - - - - - -
Roleystone - 0.2 - - - 0.2 8.6 1.0 - - - - - 0.8 - - 2.6













Rottnest Island - - - - - - 6.4 - - - - - - - - - 0.2 - - - - - - - - - - - - - -
Serpentine - - - - - - 14.6 - - - - - - 1.2 - - 0.2 - - - - - - - - - - - - - -
Swanbourne - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.

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 Thursday 31 January 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, 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 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.

Further information

Media
(03) 9669 4057
Enquiries