Adelaide Metro & Hills in December 2010: Well above average rainfall with several rainfall records broken

  • The wettest December on record in Adelaide.
  • Nine other locations in South Australia also had their wettest December on record.
  • Fifteeen locations set new highest daily rainfall records for December, including Adelaide.
  • Very high to highest December rainfall on record right across the Metro & Hills area.
  • Above average thunderstorm activity in Adelaide.
  • Maximum temperatures close to average, with minimum temperatures slightly above average.

The month started with high temperatures and humidity levels due to a sequence of low pressure troughs around the eastern border of the state, and a persistent blocking high pressure system centred in the Tasman Sea. Through this period a sustained burst of severe thunderstorm activity occurred on the 7th December producing severe winds and intense rainfall, with some stations in the Barossa Valley and hills seeing rainfall intensity exceeding 1 in 100 average recurrence levels. About mid-month this gave way to a milder south-westerly air-stream which was maintained through much of the remainder of the month.

Rainfall

Rainfall totals were well above average this month, with monthly totals up to five times the December average. Fifteen locations set new daily rainfall records for December. Most of these records were set during a prolonged period of severe thunderstorm activity on the afternoon and evening of the 7th December, with the rainfall totals being read to 9am on 8 December. Ten locations also had their wettest December on record.

Adelaide (Kent Town) rainfall for December 2010 was 87.0mm recorded on 12 days (this rainfall total is from the manually observed 203mm rain gauge which is used for the long term rainfall record. This may differ from totals on the Bureau's webpage which may be from the automatic tipping bucket rain gauge). This rainfall total is 59.0mm above the Kent Town average of 28.0mm on 8 days, while median December rainfall is 24.4mm. Last December's rainfall total recorded at Adelaide (Kent Town) was 18.2mm. This is the highest December rainfall since records began at Adelaide (Kent Town) in 1977. The previous highest was 72.8mm in 1993. Adelaide (Kent Town) also recorded it wettest single December day on record on the 8th, across both the Kent Town and West Terrace record. This is also the new highest daily rainfall record across all months of the year at Kent Town, but not at the West Terrace site where the wettest day on record saw 141.5mm fall on 07 February 1925.

Rainfall totals ranged from about 20mm to 130mm across the metropolitan area, increasing up to about 150mm in the Adelaide Hills. The highest reading was 207.0mm at South Para Reservoir.

For 2010 overall, Adelaide (Kent Town) recorded 592.6mm which is 43.5mm above the long-term average of 549.1mm. Last year 517.2mm was recorded. Rainfall totals were average to above average elsewhere across the Adelaide Hills and Metropolitan area for the whole of 2010. See the South Australia in 2010 annual summary for more information.

Temperatures

Mean maximum temperatures were mixed, but generally close to average across the Adelaide Hills and Metropolitan area. The mean maximum temperature at Adelaide (Kent Town) was 26.7C which is 0.3C below the long-term December average. Adelaide (Kent Town) had three days where the maximum temperature exceeded 35C, which is equal to the long-term average for December of 3 days. In comparison, December last year there was a total of 7 days at or above 35C, which included 2 days above 40C.

The coldest day recorded at Adelaide (Kent Town) in December this year was 17.6C on the 19th.

The highest daily maximum temperature in the Adelaide and Adelaide Hills region was 40.5C recorded at Edinburgh RAAF on the 31st. The lowest daytime temperature was 11.3C recorded at Mount Lofty on the 10th.

Minimum temperatures were close to 1.0C above average this December. The mean minimum temperature at Adelaide (Kent Town) was 16.0C, which is 0.5C above the long-term December average of 15.5C. In December last year Adelaide (Kent Town) recorded a mean minimum of 15.9C.

The lowest daily minimum temperature in the Adelaide and Adelaide Hills region was 5.4C recorded at Mount Barker on the morning of the 22nd, whilst the warmest night was 26.4C at Adelaide (Kent Town) and at Parafield Airport on the 5th.

A sequence of low pressure troughs through eastern South Australia in the first half of December saw increased humidity levels, with Adelaide (Kent Town) recording an average 3pm relative humidity of 46% over the first 15 days of December, compared to the December average of 39%. For the month as a whole, the average 3pm relative humidity returned to normal with 39.6% recorded at Kent Town for December 2010.

Some sites had their highest total December rainfall on record.
Some sites had their highest total December rainfall for at least 25 years.
Some sites had their highest December daily rainfall on record.

 

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Extremes in December 2010
Hottest day 40.5 °C at Edinburgh RAAF on the 31st
Warmest days on average 27.7 °C at Parafield Airport
Coolest days on average 20.8 °C at Mount Lofty
Coldest day 11.3 °C at Mount Lofty on the 10th
Coldest night 5.4 °C at Mount Barker on the 22nd
Coolest nights on average 11.0 °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 5th
26.4 °C at Parafield Airport on the 5th
Warmest on average overall 21.6 °C at Parafield Airport
Coolest on average overall 16.1 °C at Mount Lofty
Wettest overall 207.0 mm at South Para Resv (Saw)
Highest wind gust 80 km/h at Edinburgh RAAF on the 7th
80 km/h at Parafield Airport on the 19th

Record highest December daily rainfall
Highest daily rainfall
in December 2010 (mm)
Previous wettest
for December
Years of
record
Gumeracha 73.4 on the 8th 58.4 on the 27th in 1920 127
Williamstown 94.6 on the 8th 45.7 on the 27th in 1920 126
Lyndoch 86.4 on the 8th 39.9 on the 25th in 1946 124
Adelaide (Glen Osmond) 64.8 on the 8th 53.1 on the 23rd in 1913 113
Smithfield 68.8 on the 8th 45.7 on the 27th in 1920 107
Gawler Council Depot 72.8 on the 8th 35.6 on the 19th in 1922 84
Parafield Airport 51.2 on the 8th 47.0 on the 28th in 1929 63
Williamstown (South Para Reservoir) 59.6 on the 2nd 38.6 on the 22nd in 2007 43
Adelaide (Magill Secure Care Centre) 63.0 on the 8th 54.8 on the 14th in 1993 42
Edinburgh RAAF 58.8 on the 8th 35.4 on the 14th in 1993 39
Bolivar Treatment Works 43.4 on the 8th 28.2 on the 14th in 1993 38
Adelaide (Kent Town) 66.2 on the 8th 37.4 on the 14th in 1993 34
Adelaide (Hope Valley Reservoir) 49.2 on the 8th 47.2 on the 14th in 1993 32
Blackwood (Wittunga) 54.0 on the 8th 42.5 on the 14th in 1993 32
Kensington Upper (Burnside) 67.2 on the 8th 57.2 on the 23rd in 1913 32



Record highest total December rainfall
Total rainfall
for December 2010 (mm)
Previous wettest
for December
Years of
record
Average for
December
Bridgewater 160.5 148.6 in 1992 135 42.0
Williamstown 167.0 115.4 in 1992 131 30.0
Lyndoch 160.0 107.2 in 1992 124 26.6
Smithfield 129.8 109.5 in 1966 113 25.4
Gawler Council Depot 118.8 109.7 in 1861 105 23.3
Edinburgh RAAF 127.0 76.4 in 1992 39 25.1
Bolivar Treatment Works 70.0 65.5 in 1992 38 24.8
Adelaide (Kent Town) 87.0 72.8 in 1993 34 29.9
Adelaide (Hope Valley Reservoir) 87.0 84.2 in 1993 32 32.1
Kensington Upper (Burnside) 100.6 76.3 in 1913 32 29.9

Highest total December rainfall for at least 25 years
Total rainfall
for December 2010 (mm)
Most recent December
at least this wet
Years since
wetter
Average for
December
Two Wells 94.8 105.4 in 1922 88 22.3
Gumeracha 145.2 149.2 in 1922 84 34.8
Adelaide (Glen Osmond) 92.6 101.3 in 1929 81 29.7
Woodside 113.2 130.0 in 1929 68 32.7
Parafield Airport 81.4 99.3 in 1929 62 25.2
Adelaide (Pooraka) 67.0 78.5 in 1966 42 25.0
Adelaide (Morphett Vale) 63.2 64.2 in 1966 25 25.8



Summary statistics for December 2010
Maximum temperatures
for December
(°C)
Minimum temperatures
for December
(°C)
Rainfall
for December
(millimetres)
Mean for
December
2010
Diff
from
average
Highest for
December
2010
Mean for
December
2010
Diff
from
average
Lowest for
December
2010
Total for
December
2010
Average
for
December
Rank of
December
2010
Fraction of
December
average
Adelaide (Kent Town) 26.7 -0.3 39.6 30th 16.0 +0.5 11.3 22nd 87.0 28.0 highest 311%
Adelaide Airport 25.9 +0.2 39.2 30th 15.5 +1.0 9.9 22nd 36.8 24.2 high 152%
Edinburgh RAAF 27.0 -0.8 40.5 31st 15.5 +0.8 9.7 22nd 127.0 25.1 highest 506%
Mount Barker 24.6 -0.4 36.1 30th 11.5 +1.1 5.4 22nd 108.6 35.0 v high 310%
Mount Lofty 20.8   33.1 30th 11.0   6.2 20th 127.6
Noarlunga 25.5   38.4 30th 15.5   10.9 19th 23.0
Parafield Airport 27.7 +0.1 39.8 30th 15.5 +0.7 10.3 20th 81.4 25.2 v high 323%

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 7 am on Tuesday 4 January 2011. 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