Monday, 30 April 2012 - Monthly Climate Summary for Perth - Product code IDCKGC11L0

Perth in April 2012: Wet start and finish

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

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Rainfall

Rainfall totals in April 2012 were generally near average in the Perth Metropolitan area, however some sites recorded above average rainfall, particularly in the western suburbs, where heavy falls in the last two days of April significantly boosted totals. Contributions also came from a number of other cold front and a low passages during the month. Roleystone observed the highest total in the Perth area for the month with 87.4 mm, which is also its wettest April since the 139.6 mm in 2008.

A westerly airflow produced mainly light showers to the coastal plain in the Perth area in the first few days of April, though sites in the Perth hills received moderate falls. A cold front moving through the Perth area brought further light to moderate rainfall on the morning of the 5th, but was followed by a lengthy dry period of almost two weeks before a cold front passed through the Perth metropolitan area on the 18th bringing rainfall totals of generally less than 10 mm. The 22nd saw the passage of a weak cold front with daily totals of less than 5 mm across the Perth area before a low pressure system off the west coast moved through the Perth area on the 28th and 29th and brought significant rainfall, with totals in the 20 to 60 mm range during the event. The daily rainfall total of 56.2 mm on the 28th at Swanbourne was the highest daily total of the month in the Perth area, and was Swanbourne's second wettest April day in 17 years of record.

Perth Metro recorded 69.2 mm of rainfall during April 2012, which is the wettest April for 4 years since 153.6 mm was recorded on 13 rain days in 2008. For the first four months of the year (January to April), Perth Metro has recorded 111.8 mm of rainfall on 16 rain days, which is above the average of 85.5 mm on 15.2 rain days and the wettest start to the year (January to April) since 215.4 mm was recorded on 18 rain days in 2008.

Maximum temperature

Mean maximum temperatures in April 2012 were generally in the mid-twenties across the Perth Metropolitan area, and in the near average to above average range.

The Perth area experienced a hot day on the 10th with daily maxima for most sites in low to mid-thirties as a strong high pressure system in the Bight directed hot northerly air over the Perth area. Pearce and Perth Airport recorded the highest temperature of the month with 35.9 °C on the 10th. The coolest day of the month over the Perth area was on the 21st as the result of a cool southerly flow, with daily maxima in the high teens and low twenties. The temperature at Bickley only reached 17.8 °C, the coldest day of the month in the Perth metropolitan area.

Perth Metro's mean maximum temperature in April was 26.4 °C, which is close to the April average of 25.7 °C. Perth Metro's maxima ranged from 21.9 °C on the 21st to a hot 35.4 °C on the 10th.

The mean maximum temperature at Perth Metro for the first four months of 2012 (January to April) was 30.6 °C, which is the 3rd hottest start to the year since records commenced in 1897, only behind 31.5 °C in 2011 and 31.3 °C in 1978. April also continues the run of above average mean monthly maxima at Perth Metro since August 2010, where 19 of the past 21 months have seen above average mean monthly maximum temperatures.

Minimum temperature

Mean minimum temperatures in April 2012 were generally in the 13 to 17 °C range, and close to average or above average for most sites in the Perth metropolitan area.

Most sites experienced a relatively warm start and end to April with warm nights (a warm night is daily minimum temperature 20 °C or above) recorded at most sites on the 4th and again on the 28th due to cloudy and overcast conditions following a warm day. The overnight temperature of 23.4 °C at Pearce on the 28th was the warmest night of the month for the Perth area. Average to below average minimum temperatures were recorded during middle parts of the month, with the coolest nights at most sites being recorded on the 6th and 21st. A minimum of 5.6 °C at Pearce RAAF on the 21st was the coldest night recorded in Perth during April 2012.

Perth Metro's mean daily minimum temperature in April was 14.3 °C, close to the average of 13.6 °C. Daily minima ranged from a cool 9.2 °C on the 21st to a warm 20.9 °C on the 4th.

Sunshine

Perth recorded an average daily sunshine of 8.0 hours in April 2012, which was the least sunniest April for 8 years since an average of 7.9 hours per day was recorded in 2004. The average sunshine for Perth in April is 8.3 hours per day.

emes 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

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