Adelaide Metro & Hills in May 2012: Cold nights and a wet end to autumn

  • Above average rainfall, typically 20% greater than average on the Adelaide plains, closer to average through the Adelaide hills.
  • Cool daytime temperatures with the coldest May day in 25 years.
  • Night time temperatures below average and coolest since 2006.

Rainfall

The May 2012 rainfall total at Adelaide (Kent Town) was slightly above average, with 62.8 mm received on 13 rain days. This is compared to the long-term average of 60.0 mm on 14 rain days, with a median rainfall of 59.8 mm. By comparison, during May 2011, 61.8 mm was recorded.

The wettest periods for the Adelaide and Hills region occurred during the first and last week of May. Much of the rainfall observed for the month came from cold frontal systems, followed by moist south to southwesterly airstreams being directed across South Australia. Despite the first week of May being wet, rainfall remained well below average across the Adelaide region up until the 23rd when a low pressure system with an associated cold front crossed the southern coastal regions of the State. This event produced significant totals in the Adelaide Hills in the persistent moist southerly airstream that followed.

Rainfall totals for May 2012 typically ranged from 40 to 60mm across the Adelaide Plains while totals of 80 to 110mm were observed in the Hills. The wettest location for the month was at Macclesfield in the Hills where 134.6mm was recorded for the month, most of that occurring in the last week of May.

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 mostly below average across the Adelaide Plains during May 2012, though tending to slightly above average at some locations in the Adelaide Hills. With respect to minimum (over night) temperatures, the coldest periods occurred between the 15th and 20th as a high pressure system maintained mostly fine and clear conditions across the State. The coldest period, with respect to daytime maximum temperatures, occurred in the latter period of the month when maximum temperatures were up to 6 C below average in the wake of the passage of a cold frontal system.

The average maximum temperature recorded at Adelaide (Kent Town) for May 2012 was 18.2C, 0.8C below the long-term mean maximum temperature of 19.0C. In comparison, May 2011 saw average maximum temperatures of 18.0C at Adelaide (Kent Town). The record highest May mean maximum in Adelaide is 22.0C set in 1934 at the West Terrace site.

The coldest day for May 2012 was reported at Mount Lofty on the 24th when the maximum reached 6.3C, Adelaide (Kent Town) also recorded a maximum of 12.3 C on this day, its coldest May day in 25 years.

The hottest day across the Adelaide and Hills region was reported at Edinburgh RAAF with a maximum of 29.3 C on the 8th and the warmest days on average were at Parafield Airport with a monthly average of 18.7 C.

Mean minimum temperatures were close to 1C cooler than average this May. While some locations on the Adelaide Plains were slightly cooler than average, hills locations tended to be slightly warmer than average by up to 0.3 C owing to above average cloud cover.

The mean minimum temperature for May 2012 at Adelaide (Kent Town) was 9.3C, 0.9 C below the long term May average of 10.2 C. This resulted in the coolest May since 2006. By comparison, May 2011 saw minimum temperature for the month average 10.0 C.

The coldest minimum temperature recorded during May 2012 in the Adelaide and Hills area was 0.0 C on the 16th at Mt Barker, whilst the coolest nights on average were recorded at Mount Lofty with 6.8 C. The warmest night was 16.4C at Noarlunga on the 1st. Noarlunga also recorded the warmest nights on average with a monthly average 10.5 C

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Extremes in May 2012
Hottest day 29.3 °C at Edinburgh RAAF on the 8th
Warmest days on average 18.7 °C at Parafield Airport
Coolest days on average 12.2 °C at Mount Lofty
Coldest day 6.3 °C at Mount Lofty on the 24th
Coldest night 0.0 °C at Mount Barker on the 16th
Coolest nights on average 6.8 °C at Mount Lofty
Warmest nights on average 10.5 °C at Noarlunga
Warmest night 16.4 °C at Noarlunga on the 1st
Warmest on average overall 14.0 °C at Noarlunga
Coolest on average overall 9.5 °C at Mount Lofty
Wettest overall 134.6 mm at Macclesfield
Driest overall 49.8 mm at Adelaide Airport
Wettest day 31.2 mm at Mount Barker on the 25th
Highest wind gust 78 km/h at Edinburgh RAAF on the 23rd




Summary statistics for May 2012
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2012
Diff
from
average
Highest for
May
2012
Mean for
May
2012
Diff
from
average
Lowest for
May
2012
Total for
May
2012
Average
for
May
Rank of
May
2012
Fraction of
May
average
Adelaide (Kent Town) 18.2 -0.8 27.4 8th 9.3 -0.9 4.6 16th 62.8 60.0 average 105%
Adelaide Airport 18.0 -0.5 26.2 8th 8.7 -0.8 3.8 16th 49.8 53.8 average 93%
Edinburgh RAAF 18.5 -0.6 29.3 8th 8.0 -1.1 2.7 16th 58.2 44.1 high 132%
Mount Barker 15.4 -1.1 24.8 8th 7.0 +0.3 0.0 16th 106.4 87.7 average 121%
Mount Lofty 12.2   22.2 8th 6.8   3.0 24th 116.8
Noarlunga 17.4   23.9 8th 10.5   7.1 3rd 51.4
Parafield Airport 18.7 -0.2 28.7 8th 7.7 -1.7 2.6 16th 63.6 47.8 high 133%

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 11 am on Thursday 31 May 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