Tuesday, 3 May 2016 - Seasonal Climate Summary for Northern Territory - Product code IDCKGCC2R0

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.

Extremes Maps Records Summaries Important notes the top

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.

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

Maps
	Observed	Anomaly	Decile rank
Total rainfall

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Month by month
Rainfall rank	Maximum temperature rank	Minimum temperature rank
October 2015: Very dry, mostly very warm
November 2015: Very dry in the north, hot throughout
December 2015: Monsoon breaks dry spell, delivers record rainfall
January 2016: Hot and dry in the north
February 2016: Hot everywhere, dry in the north
March 2016: Wet in the south, dry in the north. Hot throughout.
April 2016: Hot and dry end to wet season
Rainfall rank	Maximum temperature rank	Minimum temperature rank

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

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

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top