Perth in autumn 2013: Above average rainfall

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.
    • Rainfall: above average
    • Maximum temperature: near average
    • Minimum temperature: above average

    Rainfall

    Autumn 2013 saw above average rainfall across the Perth metropolitan area as the result of a wet March, a below average April, and an above average May. Rainfall totals were generally in the 210 mm to 250 mm range for autumn.

    Significant rainfall events during autumn 2013 in Perth:

    • A middle level trough produced light to moderate rainfall in the Perth metropolitan area on 10 March and the morning on the 11th as a number of sites reported rainfall in the 10 to 20 mm range. This was the heaviest rainfall for many sites since mid-December.
    • A significant rainfall event occurred on 14 May as a result of a nearby middle level trough, with daily totals in this event mostly in the 20 and 30 mm range across the metropolitan area.
    • A strong cold front produced a third notable rainfall event in March on the evening of the 25th and morning of the 26th with rainfall totals in Perth generally in the 15 to 25 mm range.
    • In a relatively dry April, a number of rainfall events occurred although most produced only light falls. The heaviest rainfall occurred during the afternoon of 21 April and morning on the 22nd as a cold front moved through the Southwest Land Division (SWLD), bringing falls to the Perth area in the 6 mm to 12 mm range.
    • Significant falls occurred in May on the 1st and 2nd, 8th to 11th, 16th to 20th, and 26th to 30th, with above average rainfall for May reported throughout Perth. The most significant falls of the month occurred as a strong cold front moved through the Perth region in the morning and early afternoon on the 8th, resulting in thunderstorms with strong winds and a wind gust to 106 km/h at Rottnest Island in the early afternoon, and moderate to heavy rainfall. A daily rainfall total of 61.6 mm at Rottnest Island in the 24 hours to 9am on the 8th was the highest daily rainfall of autumn in the Perth area, and was Rottnest Island's wettest autumn day for twenty years, since 65.0 mm was recorded on 18 May 1993.

    Perth Metro recorded 228.8 mm of rainfall on 29 rain days during autumn 2013, which was above the average of 180.1 mm on 21.9 rain days. Rainfall totals at Perth Metro for the individual months in autumn 2013 were: March: 69.6 mm (average 19.2 mm), April: 21.0 mm (average 44.1 mm), and May: 138.2 mm (average 116.8 mm). Perth Metro recorded its wettest autumn for five years since 227.4 mm was recorded in autumn 2008.

    Maximum temperature

    Daytime temperatures for autumn 2013 were near average across the Perth metropolitan area as the result of a cool March, a very warm April and warmest on record for a number of sites, and a near average May. Mean daily maxima for autumn were in the mid-twenties

    During autumn 2013, a number of sites on the Swan coastal plain experienced about 4 to 5 days with daily maximum temperatures over 35.0 °C. The hottest day occurred on 8 April for most sites and the highest temperature recorded during autumn was 39.4 °C at Pearce RAAF, as a result of a trough off the west coast directing northeasterly winds over the city. The coolest day of the season saw daily maxima generally in the mid-teens across the metropolitan area on 30 May, and Bickley recorded the lowest maximum temperature of the season with 11.6 °C, in the cold pool of air following the passage of a moderate cold front through Perth.

    Perth Metro's mean daily maximum temperature for autumn 2013 was 26.0 °C, which is equal to the average. Daily maxima at Perth Metro during autumn ranged from a cool 14.6 °C on 30 May to a very hot 37.3 °C on 8 April. Perth Metro saw a strong contrast in maximum temperatures in April and May as it went from its warmest April in 117 years of record with a monthly mean of 28.5 ºC to a below average May with a mean of 21.5 ºC, thus observing a 7 ºC change in mean monthly maximum temperatures between consecutive months. On average Perth Metro would expect to see a 3.4 ºC change in mean monthly maximum temperatures between April and May.

    Minimum temperature

    Mean daily minimum temperatures during autumn 2013 were above average for most sites, with mean daily minima mostly in the mid-teens across Perth. The above average autumn was the result of a near average March, a very warm April, with records at a number of sites, and a near average May.

    During autumn 2013, most sites experienced two warm nights with daily minima over 20 °C on 10 March and 12 April. A daily minimum temperature of 25.4 °C at Pearce RAAF on 10 March was the highest overnight temperature in the Perth area in autumn. Most sites on the coastal plain and in the hills experienced 7 cold nights with daily minima below 10 °C, on 27 March,12 May, 21 to 24 May, and 31 May. The lowest temperature in autumn 2013 in the Perth area was 0.5 °C at Jandakot Aerodrome on 31 May, clearly the coldest morning of autumn 2013.

    Perth Metro's mean daily minimum temperature for autumn 2013 was 14.5 °C, which is slightly above the average of 13.6 °C. Daily minima at Perth Metro ranged from a cold 3.5 °C on 31 May, to a warm 23.0 °C on 10 March.

    Wind and Sunshine

    Perth’s mean daily sunshine was 11.0 hours per day in autumn 2013, which is close to the long term average of 11.3 hours per day.

 

Further information

Media
(03) 9669 4057
Enquiries

Extremes in autumn 2013
Hottest day 39.4 °C at Pearce RAAF on 8 Apr
Warmest days on average 26.3 °C at Perth Airport
Coolest days on average 23.5 °C at Bickley
Coldest day 11.6 °C at Bickley on 30 May
Coldest night 0.5 °C at Jandakot Aero on 31 May
Coolest nights on average 13.1 °C at Jandakot Aero
Warmest nights on average 17.5 °C at Rottnest Island
15.5 °C at Champion Lakes
Warmest night 25.4 °C at Pearce RAAF on 10 Mar
Wettest overall 280.0 mm at Bickley
Wettest day 61.6 mm at Rottnest Island on 8 May
56.8 mm at Swanbourne on 8 May
Highest wind gust 106 km/h at Rottnest Island on 8 May
94 km/h at Bickley on 8 May

Summary statistics for autumn 2013
Maximum temperatures
for autumn
(°C)
Minimum temperatures
for autumn
(°C)
Rainfall
for autumn
(millimetres)
Mean for
autumn
2013
Diff
from
average
Highest for
autumn
2013
Mean for
autumn
2013
Diff
from
average
Lowest for
autumn
2013
Total for
autumn
2013
Average
for
autumn
Rank of
autumn
2013
Fraction of
autumn
average
Bickley 23.5 -0.2 35.1 8 Apr 13.2 +0.8 3.9 31 May 280.0 209.4 high 134%
Champion Lakes 25.5   35.8 8 Apr 15.5   3.9 31 May 212.0
Garden Island HSF 23.9 -0.4 35.7 8 Apr 16.6 +0.6 9.2 31 May 216.6 137.0 high 158%
Jandakot Aero 25.8 0.0 37.0 8 Apr 13.1 +0.8 0.5 31 May 245.0 166.7 high 147%
Perth Airport 26.3 +0.6 37.7 8 Apr 14.0 +0.9 1.6 31 May 176.0 156.4 average 113%
Perth Metro 26.0 0.0 37.3 8 Apr 14.4 +0.8 3.5 31 May 228.8 180.1 high 127%
Rottnest Island 23.8 +0.1 32.6 8 Apr 17.5 +0.4 9.6 31 May 247.0 151.7 high 163%
Swanbourne 25.9 +0.4 36.9 9 Mar 15.4 +0.4 5.0 31 May 230.8 151.4 high 152%

Notes

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

A Seasonal 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 Friday 31 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, 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