Northern Territory in May to September 2013: Hottest dry season on record

  • Northern Territory Records:
    • Highest May to September mean daily maximum temperature
    • Highest May to September mean daily temperature
    • Third highest May to September mean daily minimum temperature
  • Temperatures:
    • Timber Creek sets new August and winter NT record with 39.7 °C on the 20th
    • Alice Springs Airport ties hottest May to September period on record
  • Rainfall:
    • Four cloudband events in May for Alice Springs District
    • Top End rainfall in May sets daily and monthly records
  • Extremes:
    • Hottest day was 41.3 °C at Bradshaw on 27 Sep
    • Coldest Night was -3.4 °C at Arltunga on 22 Jun
    • Highest daily rainfall was 101.4 mm at Batchelor Aero on 24 May

Bushfires

The dry season is also bushfire season, in the NT. On 21 June the Bureau of Meteorology issued the first fire weather warning for the northern fire season. The warning area covered the greater Darwin and rural area and the Vernon area (Batchelor and Litchfield). Bushfire NT issued their first fire ban on the same day.

Although wet season rainfall was generally below average for northern Australia, the short bursts of heavy rain followed by several weeks of sunny and humid weather was ideal for vegetative growth; thus the fuel load was quite high across the Top End as the northern fire season began. By the end of June the weather had been dry enough for grasses to dry and the fire danger to increase.

Several fires burned across the Top End in the middle of the dry season (July and August). In July, the Bureau of Meteorology issued a fire weather warning on 16 days. An early July fire near Noonamah lofted smoke over the greater Darwin area and affected visibility along the Stuart Highway. August began with several bushfires burning across the Top End. At least three fires were active on the Tiwi Islands within the first week of August and a large fire burnt near the Arnhem Highway. Smoke and haze was a dominant feature of the atmosphere around Darwin early during this time in the dry season.

Timber Creek sets new NT temperature record

On August 20th, Timber Creek reached a maximum temperature of 39.7 °C. This is half a degree hotter than the previous Northern Territory record highest August (and winter) daily maximum temperate of 39.2 °C measured at Mango Farm on 25 August 1998. This new record at Timber Creek also tied the second hottest August day on record for all of Australia (39.7 °C at Wyndham Aero, WA, on 31 August 2009).

Cloudbands and Alice Springs Rainfall

In May, the sea surface temperature (SST) off the northwest coast of Australia were very much above average, with some areas nearly two degrees above the long-term average and exceeding the previous May SST temperature record. The temperature of the sea surface is an important weather ‘driver’ for the NT. Warm SSTs off the northwest coast can provide tropical moisture to cloud bands that sweep across the central part of the continent. In May the Alice Springs District saw 4 cloud band events providing ample rainfall to the region. Alice Springs Airport measured 42.6 mm in May, this is more than double their long-term average and their wettest May in 9 years. Across the whole Alice Springs District, every site measured above average rainfall with some sites recording their wettest May on record. To the North of Alice Springs, Rabbit Flat (a WMO climate reference station) and The Granites both saw their wettest May on record with 82.0 mm and 93.0 mm respectively.

In June, two significant cloudbands formed over northern WA and brought rainfall to the far southwest corner of the NT. Another cloudband event in July contributed to above average rainfall at Yulara and Alice Springs.

Rainfall

We don't often think about rainfall in the dry season. As the name suggest, the season is inherently dry. However, the NT does occasionally see rain between May and September. This season most rain fell in May. May is a transition month, which means that the air mass over the Top End has to change from warm and humid to cool and dry. The mechanism for change is related to southern winter conditions by the presence of strong high pressure systems. These systems bring cool, dry southeasterly winds from higher latitudes and dry season conditions to the Top End.

In May 2013 a southeasterly wind change reached the north coast on the 24th. As the incumbent southeasterlies met the warm humid airmass over the Top End, a series of showers were triggered which broke several rainfall records both for the month of May and for the dry season. Showers are always a possibility ahead of a southeasterly wind change as the cold dry air undercuts the warm humid air and lifts it to form cloud. What made this event distinct was the depth of moisture in the atmosphere. The warm SSTs off the northwest coast, coupled with prevailing easterly winds during the early half of May contributed to a deep layer of moisture and a good environment for showers on the 24th. Thus, the wettest single day in the NT this dry season was at Batchelor Aero with 101.4 mm on 24 May. It is unusual for a location in the western Top End to measure more than 100 mm in a dry season month, it is even more unusual for over 100 mm to fall in one day. Several other sites saw their highest dry season daily rainfall on record from the May 24th event including Litchfield with 91.4 mm, Territory Wildlife Park with 61.0 mm and Darwin River Ridge with 55.8 mm.

In addition to the Top End rainfall, May was an exceptionally wet month in the Alice Springs District as well. Four precipitating cloudbands moved across the Alice Sprigs District in May and Rabbit Flat and the Granites saw their wettest May on record. Cloudbands also affected the region in June and July.

The wettest overall this dry season was Batchelor Aero with 181.6 mm, followed by North East Island with 152.8 mm, and then McCluer Island with 138.6 mm.

Temperature: Hottest dry season on record

In terms of mean temperature (average of daily maximum and daily minimum temperature), the NT sweltered through the hottest dry season on record. The mean temperature for the NT this dry season was 28.1 °C, which is 1.9 °C higher than the long-term average (26.2 °C). This passes the previous mean temperature record of 27.8 °C set in 1998.

There were several potential contributing factors to the high temperatures this season. One possible cause was a negative Indian Ocean Dipole (IOD). When the IOD is negative the ocean temperatures surrounding northern and northwestern Australia tend to increase. Not only does this provide extra heat into the air over coastal regions, it may also change the weather patterns over the continent allowing for stronger easterly winds over the Top End. A negative IOD pattern (with IOD index less than -0.4) was in place in May, June, July and early August and most likely contributed to the higher than normal temperatures in the early dry season.

Another possible contributing cause to the high temperatures was that this season saw fewer/weaker high pressure systems moving across the Great Australian Bight. These high pressure systems are essential in producing an airmass change over central and northern Australia. As a high pressure moves across the Bight it pushes cool, dry, continental air north sometimes reaching the north coast. These southerly surges usually occur three to four times each month in the dry season and bring lower temperatures and lower humidity. Where fewer of these southerly surges occurred northern Australia (and to some degree central Australia, too) remained warmer than normal and more humid for most of August.

Across the NT this season, the warmest on average was Cape Don with 28.2 °C, followed by Jabiru Airport with 27.9 °C, and then Cape Wessel with 27.4 °C. The coolest on average was Arltunga with 16.2 °C, followed by Kulgera with 16.5 °C, and then Yulara Aero with 16.6 °C.

Maximum temperature: highest on record

When averaged across the NT the mean daily maximum temperature this season was 35.3 °C, which is 2 °C above average and the highest mean daily maximum temperature on record for the NT during the dry season. Several sites, including VRD and Tennant Creek Airport, had their highest May to September temperature on record. With a mean daily maximum temperature of 24.9 °C, Alice Springs Airport tied their highest May to September mean daily maximum temperature on record. Tennant Creek Airport, Rabbit Flat, and VRD were also among the sites to set new dry season daily maximum temperature temperature records.

Bradshaw saw the three hottest days in the NT this month with 41.3 °C on the 27th, followed by 41.2 °C on the 20th, and then 41.1 °C on the 17th. It is not a surprise then that the warmest days on average were at Bradshaw with an average monthly maximum temperature of 34.9 °C, followed by Douglas River with 34.8 °C, and then Jabiru Airport and Middle Point both with 34.3 °C.

The coldest day (lowest daily maximum temperature) was at Kulgera with 9.8 °C on 19 Jun and then again on 9 Jul, followed by Curtin Springs with 10.5 °C on 9 Jul, and then Arltunga with 10.8 °C on 9 Jul. The coolest days on average were at Kulgera with 23.5 °C, followed by Arltunga with 24.4 °C,and then Curtin Springs with 24.8 °C.

Minimum temperature: 3rd highest on record

With an NT average daily minimum temperature of 20.9 °C, this dry season ranked as the third warmest on record, for minimum temperatures. The long-term average is 19 °C and the record warmest was 21 °C set in May to September 1998.

The minimum temperature at Darwin Airport dropped below 20 °C only 38 times, this season, this is 13 times fewer than average and a stark difference to the last two dry seasons which saw 94 nights below 20 in 2011 and 86 nights in 2012. Darwin had experienced only four nights below 20 °C up to 30 June, this year. There was a run of 20 nights below 20 °C between 24 July and 13 August. 2 September was the last night this season to see the temperature drop below 20 °C.

The coldest nights anywhere in the NT between May and September this year was at Arltunga with -3.4 °C on 22 Jun, followed -2.8 °C on 23 Jun, and then -2.7 °C on 21 Jun. The coolest nights on average were at Arltunga with 8.1 °C, followed by Yulara Aero with 8.4 °C, and then Alice Springs Airport with 8.5 °C.

The warmest nights across the NT this dry season was at Cape Don with 28.2 °C on 3 May, followed by North East Island with 28.1 °C on 2 May, and then McCluer Island with 27.8 °C on 7 May. The warmest nights on average were at Cape Don, Cape Wessel and McCluer Island all with a seasonal mean daily minimum temperature of 24.5 °C, followed by North East Island with 23.7 °C, and then Warruwi with 23.3 °C.

There were a few new minimum temperature records set this dry season. Kulgera and Ngayawili were among the sites to see their warmest May to September night (highest daily minimum temperature) on record. Tennant Creek Airport had their highest May to September mean daily minimum temperature on record.

Wind

The strongest wind gust was at Cape Wessel with 78 km/h on 3 May, followed by McCluer Island with 72 km/h on 4 May, Centre Island with 72 km/h on 25 May, and McCluer Island again with 72 km/h on 7 Sep.

Further information

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Extremes in May to September 2013
Hottest day 41.3 °C at Bradshaw on 27 Sep
Warmest days on average 34.9 °C at Bradshaw
Coolest days on average 23.5 °C at Kulgera
Coldest day 9.8 °C at Kulgera on 19 Jun
9.8 °C at Kulgera on 9 Jul
Coldest night -3.4 °C at Arltunga on 22 Jun
Coolest nights on average 8.1 °C at Arltunga
Warmest nights on average 24.5 °C at Cape Don
24.5 °C at Cape Wessel
24.5 °C at McCluer Island
Warmest night 28.2 °C at Cape Don on 3 May
Warmest on average overall 28.2 °C at Cape Don
Coolest on average overall 16.2 °C at Arltunga
Wettest overall 181.6 mm at Batchelor Aero
Wettest day 101.4 mm at Batchelor Aero on 24 May
Highest wind gust 78 km/h at Cape Wessel on 3 May

Maps

Month by month
Rainfall rank Maximum temperature rank Minimum temperature rank
May
Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
June
Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
July
Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
August
Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
September
Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
Rainfall rank Maximum temperature rank Minimum temperature rank

Record highest May to September daily rainfall
Highest daily rainfall
in May to September 2013 (mm)
Previous wettest
for May to September
Years of
record
Middle Point Rangers 91.4 on 24 May 74.0 on 18 May 1987 46
Litchfield 55.4 on 24 May 51.4 on 18 Sep 1984 30
Glen Helen Lodge 38.0 on 12 May 34.6 on 8 Jul 2005 22
Territory Wildlife Park 61.0 on 24 May 39.0 on 20 May 2004 21
Batchelor Aero 101.4 on 24 May 57.6 on 19 May 2007 20
Point Fawcett 61.0 on 23 May 58.0 on 13 May 1998 19
Bonalbo 24.0 on 23 May 21.5 on 28 May 2004 18
Cooinda Aerodrome 97.8 on 18 May 24.4 on 10 May 2012 18
Ludmilla 61.8 on 24 May 39.2 on 30 Sep 2012 18
Wandie Creek 64.6 on 18 May 55.0 on 30 Sep 1987 18
Groote Eylandt Airport 61.8 on 10 May 41.0 on 19 May 2004 15
Middle Point 44.6 on 24 May 42.0 on 14 Sep 2002 13
Darwin River Ridge 67.4 on 24 May 61.6 on 23 May 2010 12
Bulman 55.8 on 23 May 45.0 on 14 May 2007 11
Maningrida Aero 39.4 on 6 May 27.0 on 25 May 2012 10
Neutral Junction 34.0 on 13 May 32.2 on 17 May 2007 10



Record highest total May to September rainfall
Total rainfall
for May to September 2013 (mm)
Previous wettest
for May to September
Years of
record
Average for
May to September
Batchelor Aero 181.6 87.4 in 2010 18 37.5
Maningrida Aero 91.4 78.4 in 2010 10 35.8




Record highest May to September temperature
Highest temperature
in May to September 2013 (°C)
Previous warmest
for May to September
Years of
record
Average for
May to September
Brunette Downs 40.4 on 29 Sep 40.3 on 26 Sep 1997 50 29.3
Victoria River Downs 40.7 on 27 Sep 40.4 on 17 Sep 1971 49 31.5
Tennant Creek Airport 39.0 on 24 Sep 38.9 on 27 Sep 1997 45 27.1
Pirlangimpi 38.0 on 23 Sep 37.2 on 26 Sep 2010 31 31.9
Territory Grape Farm 38.8 on 25 Sep 38.2 on 27 Sep 2012 22 25.2
Point Fawcett 35.4 on 16 May 35.2 on 22 Sep 2005 16 30.6
Middle Point 40.0 on 19 Sep 39.4 on 19 Sep 2008 13 33.6



Record highest May to September mean daily maximum temperature
Mean daily maximum
temperature
for May to September 2013 (°C)
Previous warmest
for May to September
Years of
record
Average for
May to September
Alice Springs Airport 24.9 = 24.9 in 2002 71 22.5
Brunette Downs 31.0 30.6 in 2003 46 29.3
Victoria River Downs 33.8 33.1 in 2009 46 31.5
Tennant Creek Airport 29.1 28.7 in 2009 43 27.1
Centre Island 29.1 = 29.1 in 1988 37 28.1
Wave Hill 32.6 = 32.6 in 1992 37 30.7
McArthur River Mine 33.2 = 33.2 in 1988 32 31.8
Timber Creek 34.1 33.9 in 1998 32 32.6
Pirlangimpi 33.5 33.2 in 1998 29 31.9
Wollogorang 32.3 32.1 in 1988 28 31.0
Douglas River 34.8 34.6 in 1998 21 33.1
Rabbit Flat 30.3 30.1 in 1999 16 28.7
Groote Eylandt Airport 30.7 = 30.7 in 2009 14 30.2
Point Fawcett 31.8 31.6 in 2005 14 30.6
Arltunga 24.4 24.2 in 2002 12 22.5
Bradshaw 34.9 34.3 in 2009 11 33.3
Middle Point 34.3 = 34.3 in 2003 11 33.6


Record highest May to September daily minimum temperature
Highest daily minimum
temperature
in May to September 2013 (°C)
Previous warmest
for May to September
Years of
record
Average for
May to September
Kulgera 22.7 on 4 Sep 21.7 on 28 Sep 2005 34 7.4
Delamere Weapons Range 27.1 on 22 Sep 26.0 on 20 Sep 2008 17 16.8
McCluer Island 27.8 on 7 May 27.5 on 27 May 2004 14 23.8
Ngayawili 25.8 on 17 May 25.4 on 16 May 2010 14 20.3



Record highest May to September mean daily minimum temperature
Mean daily minimum
temperature
for May to September 2013 (°C)
Previous warmest
for May to September
Years of
record
Average for
May to September
Jervois 10.9 10.7 in 2009 44 8.0
Tennant Creek Airport 16.5 16.3 in 1996 43 14.8
Kulgera 9.7 9.4 in 1996 31 7.4
Territory Grape Farm 10.5 9.6 in 2009 17 7.9
Arltunga 8.1 8.0 in 2009 12 6.2
McCluer Island 24.5 = 24.5 in 2003 11 23.8



Summary statistics for dry season 2013
Maximum temperatures
for May
to September
(°C)
Minimum temperatures
for May
to September
(°C)
Rainfall
for May
to September
(millimetres)
Mean for
May
to September
2013
Diff
from
average
Highest for
May
to September
2013
Mean for
May
to September
2013
Diff
from
average
Lowest for
May
to September
2013
Total for
May
to September
2013
Average
for
May
to September
Rank of
May
to September
2013
Fraction of
May
to September
average
Darwin-Daly (district 14GA)
Black Point 31.0 +0.5 34.3 23 Sep 22.8 +0.8 17.8 1 Aug 10.6 45.8 average 23%
Bradshaw 34.9 +1.6 41.3 27 Sep 19.4 +2.0 7.9 3 Jul 0.6 29.3 low 2%
Cape Don 31.8   34.9 6 May 24.5   20.5 11 Aug 20.4 43.6 average 47%
Central Arnhem Plateau 31.4   37.7 24 Sep 18.1   9.7 25 Jul 49.2
Croker Island Airport 30.8   35.1 23 Sep 22.9   19.0 9 Aug 25.8
Darwin Airport 32.3 +0.9 35.2 2 May 21.6 +0.7 15.8 8 Aug 35.0 44.8 average 78%
Delamere Weapons Range 32.6 +1.2 39.4 20 Sep 18.2 +1.4 9.5 3 Jul 0 12.3 lowest 0%
Douglas River 34.8 +1.7 39.1 20 Sep 16.8 +1.7 7.5 8 Aug 6.8 21.4 average 32%
Dum In Mirrie 31.8 +0.9 36.9 3 May 21.3 +1.0 12.0 25 Jul 47.6 35.2 high 135%
Jabiru Airport 34.3 +0.9 38.8 24 Sep 21.6 +1.6 15.1 2 Jul 76.2 25.5 high 299%
Katherine Country Club 33.4   39.4 20 Sep 17.2   5.2 26 Jul 0.1
Mango Farm 33.8 +0.7 39.3 17 Sep 17.5 +0.7 8.0 8 Aug 38.2 22.1 high 173%
McCluer Island 28.5 +0.2 31.9 22 Sep 24.5 +0.7 20.8 2 Jul 138.6 68.0 high 204%
Middle Point 34.3 +0.7 40.0 19 Sep 17.5 +1.1 7.7 5 Aug 77.2 41.7 high 185%
Murganella Airstrip     38.9 22 Sep 19.6   10.9 4 Aug 22.0
Pirlangimpi 33.5 +1.6 38.0 23 Sep 21.2 +1.4 14.1 26 Jul 14.8 63.6 low 23%
Point Fawcett 31.8 +1.2 35.4 16 May 20.0 +0.3 13.3 7 Aug 115.2 56.8 high 203%
Point Stuart 32.0   35.0 22 Sep 20.6   12.3 4 Aug 39.4 20.8 high 189%
Tindal RAAF 33.2 +1.3 38.9 23 Sep 16.6 +0.5 7.0 26 Jul 11.0 14.3 high 77%
Arnhem (district 14BC)
Cape Wessel 30.4   32.8 1 May 24.5   20.4 23 Sep
Gove Airport 29.7 +0.8 34.2 21 Sep 21.1 +0.5 11.5 8 Aug 128.0 151.3 average 85%
Groote Eylandt Airport 30.7 +0.5 36.1 13 Sep 17.9 +1.3 9.4 9 Aug 81.2 41.3 high 197%
Maningrida Aero 31.4   37.7 22 Sep 20.4   12.7 9 Aug 91.4 35.8 highest 255%
Milingimbi 31.2   34.6 21 Sep 21.1   14.9 7 Aug 52.0 43.8 average 119%
Ngayawili 30.8 +0.4 33.1 18 May 21.3 +1.0 15.0 9 Aug 15.2 47.4 low 32%
North East Island 29.1   32.9 1 May 23.7   19.0 10 Aug 152.8 45.1 v high 339%
Warruwi 30.3 +0.6 37.0 22 Sep 23.3 +0.8 18.2 8 Aug 50.6 21.0 high 241%
Roper-Mcarthur (district 14DE)
Centre Island 29.1 +1.0 35.2 13 Sep 21.3 +0.9 15.8 2 Jul
Daly Waters 33.1 +2.3 39.2 23 Sep 14.6 +0.4 3.5 26 Jul 0.6 14.5 average 4%
McArthur River Mine 33.2 +1.4 39.7 26 Sep 16.5 +2.1 6.5 25 Jul 1.2 16.4 average 7%
Ngukurr 33.0   40.0 20 Sep 17.3   7.5 9 Aug 11.0
Wollogorang 32.3 +1.3 39.1 18 Sep 14.1 +0.6 5.4 26 Jul 6.9 13.2 average 52%
Victoria (district 14F)
Timber Creek 34.1 +1.5 41.0 27 Sep 17.5 +0.6 7.4 3 Jul 2.4 18.3 average 13%
Victoria River Downs 33.8 +2.3 40.7 27 Sep 16.0 +2.0 4.6 26 Jul
Wave Hill 32.6 +1.9 40.4 24 Sep 15.7 +2.3 3.3 26 Jul 3.6 27.0 average 13%
Barkly (district 15A)
Brunette Downs 31.0 +1.7 40.4 29 Sep 14.9 +1.7 6.4 1 Jul 16.0 26.3 average 61%
Tennant Creek Airport 29.1 +2.0 39.0 24 Sep 16.5 +1.7 7.0 23 Jun 24.1 28.1 average 86%
Alice Springs (district 15B)
Alice Springs Airport 24.9 +2.4 38.1 25 Sep 8.5 +1.8 -1.1 25 Jul 91.2 65.3 high 140%
Arltunga 24.4 +1.9 37.3 25 Sep 8.1 +1.9 -3.4 22 Jun 63.8 57.8 average 110%
Curtin Springs 24.8 +1.8 37.5 22 Sep 8.6 +2.0 -0.5 23 Jul 75.5 62.4 average 121%
Jervois     40.4 24 Sep 10.9 +2.9 1.1 22 Jun 62.4 59.6 average 105%
Kulgera 23.5 +1.6 36.0 23 Sep 9.7 +2.3 0.1 23 Jul 75.2 63.5 high 118%
Rabbit Flat 30.3 +1.6 40.1 24 Sep 11.3 +1.5 0.7 26 Jul 73.4 34.3 high 214%
Territory Grape Farm 26.9 +1.7 38.8 25 Sep 10.5 +2.6 -0.3 25 Jul 48.0 54.4 average 88%
Walungurru 27.2   38.0 22 Sep 14.6   6.9 6 Aug 65.4 62.7 average 104%
Yulara Aero 24.9 +1.5 37.3 22 Sep 8.4 +1.2 -0.9 25 Jul 65.2 61.4 average 106%

Notes

A Seasonal Climate Summary is prepared to list the main features of the weather in Northern Territory 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 8 am on Tuesday 1 October 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 10 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.

The ACORN-SAT dataset is being used for temperature area averages from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.

Further information

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