Adelaide Metro & Hills in December 2012: A warm and dry end to the year.

  • Rainfall was very much below average with many locations receiving less than half of long term December average rainfall.
  • Adelaide's warmest December in 3 years.
  • Adelaide observed it's hottest December day in 5 years.

Rainfall

The December 2012 rainfall total at Adelaide (Kent Town) was 11.6 mm received on 6 rain days. This is nearly 40% of the long term December average of 29.4 mm usually received on 7 rain days. The rainfall total this month results in the driest December for Adelaide since 2002 when only 9.0 mm was observed. The long term median December rainfall for Adelaide (Kent Town) is 24.6 mm, last time exceeded in December 2010 when 87.0 mm was observed. The driest December at Adelaide (Kent Town) was observed in 1991 when just 5.8 mm was observed.

Much of the rainfall during December was recorded as a result of the passage of low pressure troughs crossing South Australia between the 1st and 4th and between the 13th and 16th.

Most locations in the Adelaide and Hills region received less than half of their long term December average with monthly rainfall totals typically ranging between 8 to 12mm on the Adelaide Plains, while higher totals in the 15 to 20mm range were observed through the Adelaide Hills. The wettest location across the region was at Smithfield where 25.2 mm was recorded for the month, 13.6 mm of which was observed on the 13th.

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.

Some sites had their lowest total December rainfall for at least 25 years.

Temperature

The average maximum temperature recorded at Adelaide (Kent Town) for December 2012 was 28.3C, 1.3C above the long term average December maximum temperature. By comparison, December 2011 saw average maximum temperatures of 27.9C. The record warmest December average maximum in Adelaide is 31.6 C, observed at the West Terrace location in 1898.

High pressure systems, clear skies with above average sunshine hours dominated the weather throughout the month. The warmest period occurred at the end of the third week of the month when Adelaide (Kent town) observed a maximum temperature of 42.0 C which was the warmest December day in 5 years. Edinburgh RAAF also observed the hottest day for any location in the region on the 23rd with 42.6 C.

Adelaide (Kent Town) reported the warmest days on average, with a monthly average of 22.2 C, which is 0.9 C above the long term December average.

Mount Lofty observed the coldest day of the month for any location in the Adelaide and Hills region when the maximum reached just 13.9 C on the 9th. The coolest days on average were at Mount Lofty where the December maximum temperature averaged 22.1 C.

Mean minimum temperatures were generally above average across the Adelaide Plains and Hills throughout the month. The minimum temperature at Adelaide (Kent Town) averaged 16.0C, 0.4 C above the long term December average. Reduced cloud cover can be attributed to the below average temperatures throughout the month.

The coldest nights through December for most locations occurred through the first week of the month following the passage of a low pressure trough and frontal system over southern parts of the state.

The coldest minimum temperature was 4.2C observed at Mount Lofty on the 6th. The coolest nights on average were recorded at Mount Lofty with 11.1 C. Mount Barker observed an average December minimum of 11.8C, 1.4C above the long term December average. The warmest night was observed at Adelaide (Kent Town) with 26.4C on the 13th. Adelaide (Kent Town) also observed the warmest nights overall, with a monthly average of 16.0 C

Further information

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Extremes in December 2012
Hottest day 42.6 °C at Edinburgh RAAF on the 23rd
Warmest days on average 29.0 °C at Parafield Airport
Coolest days on average 22.1 °C at Mount Lofty
Coldest day 13.9 °C at Mount Lofty on the 3rd
Coldest night 4.2 °C at Mount Barker on the 6th
Coolest nights on average 11.1 °C at Mount Lofty
Warmest nights on average 16.0 °C at Adelaide (Kent Town)
Warmest night 26.4 °C at Adelaide (Kent Town) on the 13th
Warmest on average overall 22.2 °C at Adelaide (Kent Town)
Coolest on average overall 18.4 °C at Kuitpo Forest Reserve
Wettest overall 25.2 mm at Smithfield
Driest overall 5.0 mm at North Adelaide
Wettest day 13.6 mm at Smithfield on the 13th
Highest wind gust 78 km/h at Edinburgh RAAF on the 12th

Lowest total December rainfall for at least 25 years
Total rainfall
for December 2012 (mm)
Most recent December
at least this dry
Years since
drier
Average for
December
Clarendon 5.2 2.2 in 1975* 35 35.5
Hahndorf 11.0 5.0 in 1984* 27 37.2

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




Summary statistics for December 2012
Maximum temperatures
for December
(°C)
Minimum temperatures
for December
(°C)
Rainfall
for December
(millimetres)
Mean for
December
2012
Diff
from
average
Highest for
December
2012
Mean for
December
2012
Diff
from
average
Lowest for
December
2012
Total for
December
2012
Average
for
December
Rank of
December
2012
Fraction of
December
average
Adelaide (Kent Town) 28.3 +1.3 42.0 23rd 16.0 +0.4 10.0 6th 11.6 29.4 low 39%
Adelaide Airport 27.0 +1.3 41.7 23rd 15.5 +1.0 9.1 6th 7.2 24.0 low 30%
Edinburgh RAAF 28.6 +0.8 42.6 23rd 15.1 +0.3 7.7 6th 10.2 24.9 low 41%
Kuitpo Forest Reserve 24.2   38.3 23rd 12.6   8.0 10th 9.0
Mount Barker 26.1 +1.1 40.5 23rd 11.8 +1.4 4.2 6th 11.0 34.8 low 32%
Mount Crawford (Mt Crawford AWS) 26.5   39.2 23rd 12.4   6.8 10th 18.8
Mount Lofty 22.1   33.8 12th 11.1   5.5 10th 19.6
Noarlunga 26.4   40.9 23rd 15.6   10.1 6th 10.8
Parafield Airport 29.0 +1.3 42.2 23rd 15.0 +0.2 7.1 6th 8.6 24.9 low 35%

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 1 pm on Wednesday 2 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 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