Northern Territory wet season, October to April 2015-16: Warmest on record, very dry in the north

Summary

A very dry 'build-up', during October to mid-December, was broken by the first and most significant period of monsoonal activity for the Northern Territory', in late December. Rainfall associated with the active monsoon burst between 21 and 29 December produced the wettest December on record for the NT. By January, dry conditions returned to most districts, particularly the Top End. Some regions south of the Top End saw average to above average rainfall during the February to April period and on top of the wet December, ended up receiving average or greater rainfall totals for the wet season. The Top End, however, was mostly dry in each month of the wet season apart from December, and ultimately finished with significantly less than average rainfall totals. The Arnhem District was the hardest hit region in the Territory with many sites in the area, including Gove Airport, Jabiru Airport and Maningrida Airport, recording their lowest wet-season rainfall on record. Darwin Airport had its driest wet season since 1991-92, with only 1118.6 mm, compared to the average of 1681 mm. Territory-wide, rainfall totals in the wet season were very close to the long-term average of 502.6 mm.

The dry start to the wet season was reflected strongly in the above average temperatures. Daytime, overnight and mean temperatures were generally above average throughout the Territory in each month, apart from during the wet December. The area-average mean temperature for the NT in the October to April period was 1.13 °C above average, the highest on record, surpassing the previous high set in 2005. The mean daily maximum was 1.34 °C above average, the third highest and the mean daily minimum temperature was the second highest on record, 0.93 °C above average. Darwin Airport had its highest October to April mean and mean daily maximum temperatures.

  • Hottest wet season on record for the NT
  • Average rainfall overall, but very dry in the Top End
  • Wettest December on record
  • Monsoon onset at Darwin on 21 December 2015
  • No tropical cyclones in the Northern Region, for only the second time since 2001/02. Record low tropical cyclone season for Australian region with only 3 recorded.
  • Seasonal detail

    The low rainfall totals and above-average temperatures experienced during the 'build-up' months of October and November and a portion of December were consistent with the background climate of a strong El Niño which matured in May 2015. During this early part of the wet season, Australia was also impacted by a positive phase of the Indian Ocean Dipole, another broadscale climate driver which likely contributed to lower than average rainfall in the NT.

    The Northern Territory had warmer than normal maximum temperatures over nearly all parts during October and November. Southern parts experienced much greater than average maximum temperatures during October, while in November the very warm temperatures predominantly affected the Top End. October had the second highest monthly mean maximum (highest since 1988) temperatures and ninth highest monthly mean temperatures on record. Territory-wide, November had the fourth highest monthly mean daily maximum and minimum and eighth highest monthly mean temperatures ever recorded. Below average rainfall was a feature for almost the entire NT during October, whereas in November western and southern parts of the Territory experienced above average rainfall due to the passage of several low-pressure troughs across the region.

    After a relatively dry and mostly warm start to December, the arrival of the first active monsoon period for the wet season brought widespread rainfall to the Territory in the second half of the month. The Daly River region in the western Top End experienced very heavy falls including more than 500 mm in 72 hours at some locations as a tropical low embedded in the monsoon trough moved over the Top End, and then down the east coast of the NT. Major flooding occurred on the Daly River. Nearly all locations in the Territory received above average rainfall during the month, with many sites receiving record daily and monthly totals. An area which extended from the southwest of the Top End, through central parts of the NT and across the Barkly saw record December rainfall. The southwest of the NT and the central and eastern Top End had rainfall totals nearer to the long-term average. Territory-wide, December rainfall was the highest on record.

    After a very wet December, the dissipation of monsoonal conditions by the start of January led to below average rainfall for much of the Territory, particularly in the north. Many locations over the Top End and the Gulf country had their lowest January rainfall on record. The south of the NT had generally average to above average rainfall during the month. The dry conditions continued into February, the Territory's driest since 2005. The January to April period was particularly dry over the Top End. By area-average it was the second driest January to April period since records began in 1910; only 1952 was drier over the Top End. Many sites had their lowest rainfall total on record. Darwin Airport was one such location, having its driest January to April period since 1941, when records began.

    The start to the year was also much warmer than average. While above average temperatures were generally confined to the Top End in January, from February through to April, virtually every part of the NT had above average temperatures. February had the eighth highest mean daily maximum and tenth highest mean temperature (highest since 1989 and 1998, respectively). March had the highest mean daily minimum temperatures on record, beating a record set in 1947, the fourth highest mean (highest since 1992) and tenth highest mean daily maximum temperatures. April had the second highest mean and third highest mean maximum temperatures on record (both highest since 2005).

    Darwin Airport set several climate records in the 4-month period from January to April: lowest rainfall (482.4 mm, compared with the average of 1220 mm), highest mean daily maximum and minimum temperatures and highest mean temperatures. Other temperature records were set at Darwin Airport during the wet season: highest mean daily maximum temperatures in November, February and April, while it was the hottest March in Darwin since 1942. April also saw the highest mean temperature, while February had the highest mean since 1964. There were 31 days above 35 °C at Darwin Airport since the start of October, more than three times the long-term average and ahead of the previous record for the equivalent period (27 in 2002-03).

    Rainfall in March was a bit of a mixed bag, with very dry conditions in the far north and generally above-average rainfall totals south of the Top End, particularly along the eastern border. The primary mechanism for the March rainfall was a series of troughs which persisted near the NT/Queensland border in the middle of the month. A secondary factor was a weak monsoon trough which developed around the same time over the eastern Top End. During the time the monsoon trough was active a tropical low developed in the Gulf of Carpentaria, but was not over water long enough to develop to tropical cyclone intensity.

    Once the monsoon trough retreated from the NT region, rainfall eased and was below average in all districts for the remainder of March. The dry conditions continued into April, the Territory's driest since 2004.

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    Extremes in October to April 2015-16
    Hottest day 44.8 °C at Rabbit Flat on 4 Jan 2016
    Warmest days on average 38.8 °C at Lajamanu Airport
    Coolest days on average 31.7 °C at McCluer Island
    Coldest day 20.9 °C at Arltunga on 31 Dec 2015
    Coldest night 6.0 °C at Arltunga on 1 Oct 2015
    Coolest nights on average 18.6 °C at Alice Springs Airport
    Warmest nights on average 27.2 °C at McCluer Island
    Warmest night 31.1 °C at Walungurru Airport on 5 Mar 2016
    Warmest on average overall 31.7 °C at Bradshaw
    Coolest on average overall 26.8 °C at Alice Springs Airport
    Wettest overall 1681.3 mm at Walker Creek
    Driest overall 123.3 mm at Watarrka
    Wettest day 291.0 mm at Willeroo on 26 Dec 2015
    Strongest wind gust 120 km/h at Rabbit Flat on 3 Nov 2015

    Maps
    Observed Anomaly Decile rank
    Total
    rainfall
    Map of Rainfall totals Map of Rainfall Anomaly Map of Rainfall Decile

    Click on a map to show it full size in a pop-up window

    Month by month
    Rainfall rank Maximum temperature rank Minimum temperature rank
    October 2015: Very dry, mostly very warm
    Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
    November 2015: Very dry in the north, hot throughout
    Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
    December 2015: Monsoon breaks dry spell, delivers record rainfall
    Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
    January 2016: Hot and dry in the north
    Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
    February 2016: Hot everywhere, dry in the north
    Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
    March 2016: Wet in the south, dry in the north. Hot throughout.
    Map of decile rank of rainfall Map of Decile rank of mean maximum temperature Map of Decile rank of mean minimum temperature
    April 2016: Hot and dry end to wet season
    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 October to April daily rainfall
    New record
    (mm)
    Old
    record
    Years of
    record
    Willeroo 291.0 on 26 Dec 2015 259.1 on 4 Mar 1935 93
    Old Delamere 162.6 on 26 Dec 2015 =162.6 on 18 Dec 1928 56
    Douglas River 244.4 on 26 Dec 2015 212.0 on 1 Feb 2014 47
    Eva Downs 196.0 on 29 Dec 2015 150.1 on 7 Feb 1969 45
    Kalala 192.0 on 24 Dec 2015 138.0 on 22 Apr 2000 39
    Andado 87.0 on 1 Jan 2016 65.0 on 30 Jan 1981 38
    Mango Farm 236.0 on 26 Dec 2015 230.2 on 18 Feb 2011 37
    Florina 250.0 on 25 Dec 2015 244.0 on 11 Jan 2001 25
    Bonalbo 230.0 on 26 Dec 2015 192.4 on 3 Mar 2000 21



    Record lowest October to April total rainfall
    New record
    (mm)
    Old
    record
    Years of
    record
    Average for
    October to April
    Gove Airport 726.2 779.2 in 2001 41 1329.7
    Pirlangimpi Airport 1268.6 1309.3 in 1984 41 1919.8
    Jabiru Airport 853.4 939.8 in 1989 39 1502.9
    Channel Island 932.7 1123.2 in 2004 31 1652.5

    Lowest October to April total rainfall for at least 20 years
    Observed
    (mm)
    Most recent
    lower
    Average for
    October to April
    Darwin Airport 1118.6 1038.2 in 1991 1673.7
    Lambell's Lagoon 911.9 861.9 in 1991* 1532.2

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




    Record highest October to April temperature
    New record
    (°C)
    Old
    record
    Years of
    record
    Average for
    October to April
    Gove Airport 38.0 on 10 Nov 2015 = 38.0 on 16 Dec 1967 38 31.9



    Record highest October to April mean daily maximum temperature
    New record
    (°C)
    Old
    record
    Years of
    record
    Average for
    October to April
    Darwin Airport 33.6 33.3 in 2012 73 32.4
    Curtin Springs 36.4 = 36.4 in 2004 48 34.3
    Centre Island 34.9 34.6 in 2014 40 33.4
    Gove Airport 33.4 33.0 in 2012 35 31.9
    Jabiru Airport 36.5 36.0 in 2012 35 34.9
    Pirlangimpi Airport 34.6 34.2 in 2014 30 32.6
    Yulara Airport 36.5 36.4 in 2012 27 34.7
    Tindal RAAF 36.8 36.2 in 2012 26 35.2
    Douglas River 36.1 36.0 in 2012 22 35.0
    Borroloola Airport 36.5 36.2 in 2012 20 35.1

    Highest October to April mean daily maximum temperature for at least 20 years
    Observed
    (°C)
    Most recent
    higher
    Average for
    October to April
    Victoria River Downs 37.8 =37.8 in 1985 36.5



    Record highest October to April mean daily minimum temperature
    New record
    (°C)
    Old
    record
    Years of
    record
    Average for
    October to April
    Curtin Springs 20.6 20.5 in 2006 48 18.4
    Warruwi Airport 26.3 26.1 in 2012 45 25.6
    Jabiru Airport 25.3 25.0 in 2012 36 24.4
    Lajamanu Airport 23.3 23.2 in 2005 20 22.2

    Highest October to April mean daily minimum temperature for at least 20 years
    Observed
    (°C)
    Most recent
    higher
    Average for
    October to April
    Centre Island 26.8 26.9 in 1987* 26.3
    Darwin Airport 25.4 25.6 in 1989 24.8

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




    Record highest October to April mean temperature
    New record
    (°C)
    Old
    record
    Years of
    record
    Average for
    October to April
    Darwin Airport 29.5 29.3 in 2004 73 28.6
    Curtin Springs 28.4 28.2 in 2006 48 26.3
    Warruwi Airport 29.8 29.6 in 2004 45 28.9
    Centre Island 30.8 30.6 in 1987 40 29.8
    Gove Airport 28.9 28.3 in 2012 35 27.8
    Jabiru Airport 30.9 30.5 in 2012 35 29.7
    Pirlangimpi Airport 29.7 29.2 in 2014 29 28.3
    Yulara Airport 28.7 28.4 in 2006 27 26.8
    Tindal RAAF 30.3 30.1 in 1987 26 29.4
    Douglas River 29.8 29.6 in 2004 22 29.1
    Lajamanu Airport 31.0 = 31.0 in 2004 20 29.3

    Highest October to April mean temperature for at least 20 years
    Observed
    (°C)
    Most recent
    higher
    Average for
    October to April
    Victoria River Downs 31.0 =31.0 in 1987 30.0



    Summary statistics for October to April 2015-16
    Maximum temperatures
    (°C)
    Minimum temperatures
    (°C)
    Rainfall
    (millimetres)
    Mean for
    October
    to April
    2015-16
    Diff
    from
    average
    Highest for
    October
    to April
    2015-16
    Mean for
    October
    to April
    2015-16
    Diff
    from
    average
    Lowest for
    October
    to April
    2015-16
    Total for
    October
    to April
    2015-16
    Average
    for
    October
    to April
    Rank of
    October
    to April
    2015-16
    Fraction of
    October
    to April
    average
    Darwin-Daly (district 14GA)
    Batchelor Airport 35.3 +1.2 39.8 18 Nov 2015 23.9 +0.5 18.1 24 Apr 2016 1153.6 1507.8 low 77%
    Bradshaw 37.8 +1.3 42.0 27 Nov 2015 25.6 +1.1 18.9 26 Apr 2016 1013.8 956.6 average 106%
    Central Arnhem Plateau 34.2   37.8 30 Oct 2015 23.1   18.7 2 Oct 2015
    Charles Point 32.6   36.8 23 Apr 2016 25.8   18.4 1 Oct 2015 1362.8
    Croker Island Airport 33.3   36.1 11 Dec 2015 25.7   20.8 15 Feb 2016  
    Darwin Airport 33.6 +1.2 36.9 8 Nov 2015 25.4 +0.6 22.0 6 Oct 2015 1118.6 1673.7 v low 67%
    Delamere Weapons Range 36.6 +1.2 41.9 26 Nov 2015 24.2 +0.6 17.9 2 Oct 2015 866.4 881.9 average 98%
    Douglas River 36.1 +1.1 41.9 24 Oct 2015 23.4 +0.4 16.0 25 Apr 2016 1261.6 1271.9 average 99%
    Dum In Mirrie Airstrip 33.0 +0.8 36.6 11 Apr 2016 25.8 +0.4 21.1 1 Oct 2015 1617.6 1732.3 average 93%
    Jabiru Airport 36.5 +1.6 41.2 8 Nov 2015 25.3 +0.9 21.2 4 Oct 2015 853.4 1502.9 lowest 57%
    Katherine Country Club 37.0   42.0 26 Nov 2015 24.1   17.0 2 Oct 2015 1177.5
    McCluer Island 31.7 +0.4 34.5 24 Feb 2016 27.2 +0.7 22.9 7 Apr 2016 435.8 1064.0 v low 41%
    Middle Point 36.2 +1.5 41.6 8 Nov 2015 23.7 +0.3 16.6 3 Oct 2015 952.6 1329.8 low 72%
    Noonamah Airstrip 35.4   39.5 8 Nov 2015 24.7   19.7 3 Oct 2015 1128.8
    Oenpelli Airport 36.4   41.7 8 Nov 2015 24.6   18.4 4 Oct 2015 818.6
    Pirlangimpi Airport 34.6 +2.0 38.4 10 Nov 2015 24.7 +0.7 21.2 3 Oct 2015 1268.6 1919.8 lowest 66%
    Point Fawcett 33.5 +1.3 36.3 8 Nov 2015 24.6 -0.3 19.4 2 Oct 2015 860.4 1460.1 v low 59%
    Point Stuart 34.2   37.4 8 Nov 2015 25.0   20.1 21 Oct 2015 806.4 1204.3 low 67%
    Port Keats Airport 34.4 +0.8 40.6 11 Nov 2015 24.9 +0.5 19.3 3 Oct 2015 1217.2 1196.5 average 102%
    Tindal RAAF 36.8 +1.6 42.2 26 Nov 2015 23.8 +0.1 15.7 3 Oct 2015 962.4 1047.3 average 92%
    Arnhem (district 14BC)
    Cape Wessel 33.5   35.6 25 Jan 2016 26.5   22.7 4 Jan 2016 710.6 1029.2 low 69%
    Gove Airport 33.4 +1.5 38.0 10 Nov 2015 24.4 +0.7 17.8 18 Nov 2015 726.2 1329.7 lowest 55%
    Groote Eylandt Airport 34.9 +1.5 39.9 10 Nov 2015 24.2 +0.6 15.5 20 Oct 2015 769.6 1252.8 v low 61%
    Milingimbi Airport 33.7 +0.8 37.0 25 Jan 2016 25.6 +0.7 20.7 19 Oct 2015 831.0 1024.4 low 81%
    Warruwi Airport 33.2 +0.9 36.5 8 Nov 2015 26.3 +0.7 23.0 17 Nov 2015 664.4 1122.9 v low 59%
    Roper-Mcarthur (district 14DE)
    Borroloola Airport 36.5 +1.4 42.9 29 Nov 2015 23.8 +0.5 16.4 3 Oct 2015 554.8 917.4 low 60%
    Bulman 37.7   42.8 9 Nov 2015 23.9   17.3 4 Oct 2015 728.2 1122.9 v low 65%
    Centre Island 34.9 +1.5 38.6 9 Nov 2015 26.8 +0.5 22.5 4 Mar 2016 794.0 1043.5 average 76%
    Daly Waters Airstrip 37.4 +1.4 43.7 10 Nov 2015 22.3 -0.4 12.9 1 Oct 2015 1017.8 661.9 high 154%
    McArthur River Mine Airport 37.8 +1.2 43.8 29 Nov 2015 24.5 +1.0 15.2 1 Oct 2015 466.6 755.4 low 62%
    Ngukurr Airport 38.4   43.7 27 Nov 2015 24.9   17.3 3 Oct 2015 462.8
    Victoria (district 14F)
    Lajamanu Airport 38.8 +2.4 43.8 5 Jan 2016 23.3 +1.1 13.4 3 Oct 2015 372.2 487.7 average 76%
    Victoria River Downs 37.8 +1.3 42.5 29 Nov 2015 24.2 +0.7 15.2 2 Oct 2015 801.0 643.3 high 125%
    Barkly (district 15A)
    Tennant Creek Airport 36.6 +1.3 42.0 2 Mar 2016 24.1 +0.8 16.9 30 Dec 2015 358.3 441.2 average 81%
    Alice Springs (district 15B)
    Alice Springs Airport 35.1 +1.9 42.6 24 Feb 2016 18.6 +0.7 6.7 25 Apr 2016 220.0 218.6 average 101%
    Arltunga 34.3 +1.4 41.7 24 Feb 2016 18.7 +0.3 6.0 1 Oct 2015 198.0 239.3 average 83%
    Curtin Springs 36.4 +2.1 43.4 2 Nov 2015 20.6 +2.2 8.3 25 Apr 2016 136.2 169.7 average 80%
    Rabbit Flat 38.7 +1.5 44.8 4 Jan 2016 22.1 +0.7 9.5 1 Oct 2015 369.4 443.7 average 83%
    Territory Grape Farm 36.5 +1.8 42.8 24 Feb 2016 20.2 +1.1 10.3 1 Oct 2015 238.6 246.6 average 97%
    Yulara Airport 36.5 +1.8 44.1 5 Dec 2015 20.8 +1.9 9.6 25 Apr 2016 135.0 213.1 average 63%

    Notes

    The Seasonal climate summary lists 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.

    A climate summary is generally published on the first working day of each month.

    This statement has been prepared based on information available at 9 am on Tuesday 3 May 2016. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

    Averages for individual sites 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 used for temperature area averages.

    Further information

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