Friday, 30 November 2012 - Monthly Climate Summary for Perth - Product code IDCKGC21L0

Perth in November 2012: A very wet month

• Rainfall: very much above average across the Perth area, and wettest on record at some sites.
• Maximum temperature: near average
• Minimum temperature: near average

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Rainfall

Rainfall across the Perth metropolitan area during November 2012 was very much above average, with monthly rainfall totals generally ranging from 40 mm to 80 mm, and grading to 130 mm in the Perth hills. Perth Airport and Bickley experienced their wettest November in 69 years and 42 years respectively, while a number of sites observed their wettest November for at least 10 years.

A cold front moved through the Perth region early morning on the 4th, with showers, thunderstorms and hail reported during the day. Most sites reported their heaviest rainfall for the month on the 4th with daily totals in the 20 mm to 30 mm range, whilst falls in the 10 mm to 20 mm range were recorded on the 5th. A westerly flow in the wake of the cold front produced mainly light showers on the 6th and 7th. A weak front moved across the Perth area in the evening on the 10th resulting in generally light showers across the Perth region. After a lengthy dry period from the 12th through to the 23rd, a deep surface trough and middle level disturbance moved across the Perth region on the 24th producing showers and thunderstorms across the metropolitan area. A line of thunderstorms developed over central parts of Perth at approximately 1100 WST on the 24th and moved southward through southern suburbs before thunderstorms to the north of Perth moved over the city in the late afternoon, with heavy falls in the northern and eastern suburbs and hail observed in northern suburbs. The daily total at Perth Airport of 26.0 mm in the 24 hours to 9am on the 25th was the third wettest day in November on record at the site, and 20.8 mm of this total fell in the 10 minutes from 1813 WST to 1822 WST on the 24th, which is a one in 20 to 50 year event. Daily totals at most other sites were generally less than 10 mm. A cold front moved across the Perth area early on the 28th, followed by a secondary front during the evening of the 28th, connected to a rapidly deepening low just off the the WA southwest coast. The systems brought widespread squally showers, very strong winds, and very high tides. Well exposed sites across the metropolitan area recorded maximum wind gusts in excess of 90 km/h, whilst coastal sites recorded wind gusts greater than 100 km/h, with the maximum gust reported during the event being 117 km/h at Rottnest Island. Most wind recording sites in the metropolitan area recorded their greatest November wind gusts for more than 10 years, and Perth Airport recorded its highest November wind gust since 1965. It was a rare occurrence for such a strong storm in late spring and the storm caused traffic congestion, with one lane closed on the Kwinana Freeway due to waves on the Swan River over-topping the sea wall, airport delays, and extensive power outages with reports of 50,000 houses losing power. Daily falls on the 28th and 29th were generally moderate with heavier falls in the Perth hills. Bickley recorded 40.4 mm on the 29th, the highest daily fall in the metropolitan area during November.

Perth Metro recorded 58.2 mm of rainfall on 8 rain days in November 2012, well above the long term November average, and the 7th wettest November since records commenced in 1876. The highest daily fall at Perth Metro during November 2012 was 26.0 mm on the 4th. Historically, November rainfall in Perth has ranged from 0.0 mm in 1891 to 73.2 mm in 1984, while last November (2011), Perth Metro recorded 29.0 mm on 8 rain days.

The total rainfall for the 2012 year to date (January to November) at Perth Metro is 588.0 mm on 96 rain days. This has been Perth Metro's 10th driest January to November period since records commenced in 1876. The long-term January to November average at Perth Metro is 836.7 mm.

Maximum temperature

Mean maximum temperatures in November 2012 were near average across the Perth region, with mean maxima around 23 °C on the islands, 24 °C in the hills, and 25 °C to 27 °C on the coastal plain.

November 2012 saw a cool to mild start, with below average maximum temperatures for the first week of the month and most sites reported their coolest day on the 4th when temperatures only reached the high teens in the wake of a cold front. Conditions warmed on the 9th in northeasterly winds ahead of a cold front with a number of sites recording maximum temperatures in the low thirties for the first warm day of the month. A weak front moved through on the 10th, with temperatures dropping to the low twenties on the 10th and 11th. Much of the remainder of the month saw mild to warm maxima, with hot days observed on the on the 17th and 21st as the result of a strong heat trough off the west coast. All metropolitan sites recorded their highest maxima of the month on the 17th or 21st and the daily maximum temperature of 36.9 °C at Pearce RAAF on the 17th was the highest temperature of the month in the Perth metropolitan area. Cool conditions due to strong cold fronts were experienced across Perth to end the month, with temperatures mainly in the high teens to low twenties.

Perth Metro's mean daily maximum temperature in November was 25.9 °C, below the average of 26.4 °C, and the first month to see a below average mean maximum temperature since February. Daily maxima at Perth Metro ranged from a hot 35.3°C on the 17th, to a mild 19.0°C on the 4th.

Perth Metro's mean maximum temperature for the 2012 January to November period is 25.2 °C, the 2nd highest from records commencing in 1897. The record warmest January to November period was set in last year (2011) with a mean maximum of 25.3 °C.

Minimum temperature

Mean minimum temperatures in November 2012 were also near average across the Perth area, with mean minima generally between 12 °C and 14 °C, 15 °C to 16 °C off the coast.

Perth nights were generally cool to mild for the first half of November with most sites recording their coolest morning of the month between the 9th and 13th. Jandakot Aerodrome recorded the lowest temperature in the metropolitan area in November with 7.2 °C on both the 10th and 13th. Many sites experienced warmer nights in the second half of November, particularly on the 17th, 18th, and 21st to 25th where temperatures were mostly in the mid to high teens. The 22nd was the warmest night of the month at most sites and the daily minimum temperature of 20.2 °C at Champion Lakes in the southeastern suburbs was the highest overnight temperature recorded during November.

Perth Metro's mean daily minimum temperature in November 2012 was 14.0 °C, close to the mean of 14.2 °C. Daily minima ranged from a mild 10.6 °C on the 5th to a warm 18.8 °C on the 22nd.

Sunshine

The mean daily sunshine hours for November was 10.7 hours, which is close to the average of 10.6 hours.

xtremes Records Summaries Important notes the top

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

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top

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.

Extremes Records Summaries Important notes the top