Adelaide Metro & Hills in July 2012: Warmer and drier than normal

  • Below average rainfall across the Adelaide Plains, though wettest July in 3 years, near average rainfall through the Adelaide Hills.
  • After a cold start, both daytime and night-time temperatures average to above average across the Plains and Hills.

Rainfall

Despite Adelaide (Kent Town) recording its wettest July in 3 years, rainfall through the month remained below average. 64.8 mm of rainfall was received on 19 rain days, almost half of which was recorded in the 24 hours to 9am on the 27th. This is compared to the long-term average of 75 mm on 16 rain days, with a median rainfall of 68.8 mm. By comparison, 61.4 mm was recorded through July 2011.

Rainfall totals for July 2012 typically ranged from 30 to 60mm across the Adelaide Plains while totals of 60 to 100 mm were observed in the Hills. The wettest location for the month across the Adelaide Plains was at Unley (Charles Street) which reported 71mm while Mount Barker in the Adelaide Hills was the wettest reporting 115.2 mm for the month.

Rainfall remained mostly well below average for the Adelaide metropolitan and Hills regions through the first 3 weeks of July 2012, though the wettest periods occurred between the 10th and 14th and again between 26th and 28th. In the earlier period, a trough of low pressure caused thunderstorms in central and eastern districts, with heavy rain and hail affecting parts of the Barossa Valley and Adelaide Hills. Large amounts of hail covered the hills around Rowland Flat and Lyndoch, taking on the appearance of snow. Most of the hail was small but some hailstones were up to 2 cm in diameter. The heavy rain caused localised flash flooding in Mount Barker. Rainfall totals in excess of 40 mm were recorded at several locations, most falling in less than an hour. The highest daily rainfall total for the month occurred at Birdwood (McVitties Hill) in the Mount Lofty Ranges, where 50.2 mm was recorded to 9 am on 13th. In the latter period, a trough of low pressure moved across southern and eastern parts of the State producing scattered showers resulting in falls generally between 20 to 30 mm to 9am on the 27th. Adelaide (Kent Town) recorded its wettest July day in 14 years with a total of 31.2mm to 9am on the 27th, Greenacres reported 44.4mm while Belair (State Flora Nursery) in the Mount Lofty Ranges reported 42mm.

The total winter 2012 rainfall to-date (June-July) for Adelaide is 191.2mm, resulting in the wettest start to winter in 8 years and just 30mm less than the long-term average winter (June-August) total rainfall of 221mm. Rainfall totals at Adelaide (Kent Town) for the year, up to the end of July, is now at 387.5mm making the January to July 2012 period the wettest since 2001.

Note that the Adelaide official climate rainfall record is taken from the manually observed 203mm rain gauge at the Kent Town site in Adelaide. These figures may differ from totals on some Bureau of Meteorology web pages as these may be from automatic tipping bucket rain gauge readings.

Temperature

Both maximum and minimum temperatures were generally near, though tending to above average across the Adelaide Metro and Hills regions during July 2012. With respect to both minimum (over night) and maximum (daytime) temperatures, the coldest periods occurred through the first week of July as a high pressure system dominated weather conditions and maintained mostly fine and clear skies across much of the State. Daytime temperatures were again below average from the 14th through to the 19th following the passage of a low pressure trough and cold frontal systems over southern parts of the State.

The average maximum temperature recorded at Adelaide (Kent Town) for July 2012 was 15.3C, exactly on the lon-term July mean maximum temperature. In comparison, July 2011 saw average maximum temperatures of 15.6C at Adelaide (Kent Town). The record warmest July mean maximum in Adelaide is 16.7C recorded in July 1975 at the West Terrace site.

The coldest day for July 2012 was reported at Mount Lofty on the 14th when the maximum reached 6.5 C; Adelaide (Kent Town) recorded its coldest day on July 1st with a maximum of only 12.6 C.

The hottest day across the Adelaide and Hills region was reported at Adelaide (Kent Town) with a maximum of 19.0 C on the 24th while the warmest days on average were at Parafield Airport with a monthly average of 15.6 C.

Mean minimum temperatures were slightly above average across the Adelaide Plains and Hills this July. The mean minimum temperature for July 2012 at Adelaide (Kent Town) was 7.8C, 0.3 C above the long term July average of 7.5C.

The coldest minimum temperature during July 2012 in the Adelaide and Hills area was -0.1 C observed at Mount Barker on the 6th. The coolest nights on average were recorded at Mount Lofty with 5.0 C. The warmest night was 12C at Noarlunga on the 25th. Noarlunga also recorded the warmest nights on average with a monthly average of 8.5 C

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Extremes in July 2012
Hottest day 19.0 °C at Adelaide (Kent Town) on the 24th
Warmest days on average 15.6 °C at Parafield Airport
Coolest days on average 9.4 °C at Mount Lofty
Coldest day 6.5 °C at Mount Lofty on the 14th
Coldest night -0.1 °C at Mount Barker on the 6th
Coolest nights on average 5.0 °C at Mount Lofty
Warmest nights on average 8.5 °C at Noarlunga
Warmest night 12.0 °C at Noarlunga on the 25th
Warmest on average overall 11.7 °C at Noarlunga
Coolest on average overall 7.2 °C at Mount Lofty
Wettest overall 115.2 mm at Mount Barker
Driest overall 22.2 mm at Mallala
Wettest day 50.2 mm at Birdwood (McVitties Hill) on the 13th
Highest wind gust 76 km/h at Mount Crawford (Mt Crawford AWS) on the 25th
76 km/h at Noarlunga on the 25th




Summary statistics for July 2012
Maximum temperatures
for July
(°C)
Minimum temperatures
for July
(°C)
Rainfall
for July
(millimetres)
Mean for
July
2012
Diff
from
average
Highest for
July
2012
Mean for
July
2012
Diff
from
average
Lowest for
July
2012
Total for
July
2012
Average
for
July
Rank of
July
2012
Fraction of
July
average
Adelaide (Kent Town) 15.3 0.0 19.0 24th 7.8 +0.3 2.3 6th 64.8 75.0 average 86%
Adelaide Airport 15.2 +0.3 18.8 12th 7.5 +0.5 1.7 6th 30.2 58.8 low 51%
Edinburgh RAAF 15.3 0.0 18.4 24th 6.1 +0.1 0.7 6th 28.6 52.2 low 55%
Kuitpo Forest Reserve 12.3   16.6 12th 6.5   2.6 7th 94.2
Mount Barker 13.2 +0.3 16.9 12th 5.2 +0.7 -0.1 6th 115.2 106.1 average 109%
Mount Crawford (Mt Crawford AWS) 11.1   14.8 12th 5.7   2.8 1st 51.2
Mount Lofty 9.4   13.3 12th 5.0   2.1 6th 95.6
Noarlunga 14.9   18.9 12th 8.5   4.0 6th 57.2
Parafield Airport 15.6 +0.5 18.8 12th 6.3 0.0 0.8 6th 33.2 58.3 low 57%
Rosedale (Turretfield Research Centre) 14.7 0.0 18.4 24th 5.7 +0.2 0.0 6th 55.9 58.9 average 95%
Roseworthy AWS 15.2   18.6 8th 5.9   -0.1 30th 24.6

Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Adelaide Metro & Hills 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 12 pm on Tuesday 31 July 2012. 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 20 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.

Further information

Media
(03) 9669 4057
Enquiries