Australia’s 2023–24 northern wet season
Issued
Summary
- Averaged across Australia north of 26°S, the wet season (October 2023 to April 2024) rainfall was 628.0 mm, which was 34% above the 1961–1990 average of 476.4 mm and the ninth-wettest on record.
- Rainfall was above average for most northern areas and the highest on record in parts of the Gregory in the Northern Territory.
- Rainfall was below average to very much below average (in the driest 10% of all wet seasons since 1900–01) for western parts of the Kimberley and Pilbara in Western Australia.
- Much of northern Australia saw a later than average northern rainfall onset date (the date when rainfall accumulated since 1 September reached 50 mm), with large areas having an onset date at least 4 weeks later than the 1981–2010 median.
- The mean maximum temperature for northern Australia's wet season was 0.92 °C above the 1961–1990 average, while the mean minimum temperature was 1.02 °C above the 1961–1990 average, the sixth-warmest on record since 1910–11.
- Waters around northern Australia were the third-warmest on record since 1900–01, at 0.69 °C above the 1961–1990 average. Sea surface temperatures (SSTs) in the Coral Sea were warmest on record in January, February and April 2024, and second-warmest on record in March.
- The wet conditions resulted in many rivers in the north running full and contributed to increased inflow to the storages. Lake Argyle and Darwin River as well as a number of storages in Queensland, including Burdekin Falls had water levels at or above their full capacities from February onwards.
- There were 8 tropical cyclones in the Australian region from October 2023 to April 2024; this compares to an average of 11 for all years since 1969–70, or 9 since 2000–01.
- Four tropical cyclones (Jasper, Kirrily, Lincoln and Megan) made landfall on the Australian mainland, which is equal to the long-term average.
- The peak of local Madden Julian Oscillation activity in January 2024 likely contributed to the start of the first active monsoon over northern Australia. At Darwin, the monsoon onset was 10 January 2024, this was delayed compared to the typical late-December onset.
Rainfall
The total area-average rainfall for northern Australia over the 2023–24 wet season (October 2023 to April 2024) was 628.0 mm, which was 34% above the 1961–1990 average of 476.4 mm. This makes the 2023–24 wet season the ninth-wettest on record (compared to all years since 1900–01).
Rainfall was above average for most of northern Australia, and very much above average (in the highest 10% of historical observations) for large parts of Queensland and the Northern Territory extending into parts of eastern Western Australia. Highest on record rainfall occurred in parts of the Gregory in the Northern Territory.
Rainfall was below average to very much below average (in the driest 10% of all wet seasons since 1900–01) for western parts of the Kimberley and Pilbara in Western Australia.
As typical of El Niño periods, much of northern Australia saw a later than average northern rainfall onset date (the date when rainfall accumulated since 1 September reached 50 mm), with large areas having an onset date at least 4 weeks later than the 1981–2010 median. This was evident in the south-west Kimberley, Pilbara and inland areas of northern Western Australia, in areas of Tanami and Barkly regions in the Northern Territory and in parts of southern and eastern Queensland.
However parts of the Kimberley in Western Australia, central and southern Northern Territory and north-western Queensland, and small pockets of the north-eastern Queensland coast experienced an earlier northern rainfall onset date.
For most of northern Australia, it was a dry start to the wet season, with overall October 2023 rainfall 86% below average, the third-driest on record (since 1900) and the driest October since 2002. In contrast, November 2023 overall rainfall was 42% above average. November 2023 rainfall was above average to very much above average (in the highest 10% of historical observations) for most of the Northern Territory and Queensland and some areas in Western Australia mostly due to multiple slow moving surface low pressure troughs and humid, unstable atmosphere.
After a drier than average December, January 2024 was the tenth-wettest on record for northern Australia. The first active monsoon period occurred in the first half of January, resulting in extensive shower and thunderstorm activity across the tropical north. The official monsoon onset date at Darwin was 10 January 2024, which was later than the average date of 29 December (the average over all years since 1957).
Wetter than average conditions continued across northern Australia in February and March 2024. For northern Australia overall, March was the second-wettest on record behind only 2011, with the rainfall total more than double the average. Large areas of inland Western Australia and central and western Northern Territory had the highest on record March rainfall.
April 2024 saw a drier end to the wet season, with large parts of Western Australia, southern Northern Territory and central Queensland recording below to very much below average rainfall.
Temperature
The mean maximum temperature for northern Australia's wet season was 0.92 °C above the 1961–1990 average, while the mean minimum temperature was 1.02 °C above the 1961–1990 average, the sixth-highest on record since 1910–11.
Mean maximum temperatures were above to very much above average (in the highest 10% of historical observations) for most of Western Australia, the Top End and the south of the Northern Territory and parts of eastern and southern Queensland. Parts of the western Gascoyne in Western Australia experienced the highest mean maximum temperatures on record for the wet season period.
Parts of the Gregory, Barkley and Carpentaria in the Northern Territory and pockets of the Gulf Country in Queensland saw below average maximum temperatures for the wet season.
Averaged across northern Australia, the mean maximum temperature was above average for each month from October 2023 to February 2024. December 2023 mean maximum temperature was 2.20 °C above average, the third-highest on record since 1910. December mean maximum temperatures were much warmer than average (in the highest 10% of historical observations since 1910) for the Northern Territory and most of Western Australia and western Queensland.
March and April 2024 were cooler than average, with northern Australia overall around 0.5 °C below average. During both months, large parts of inland Western Australia and western and central Northern Territory had mean maximum temperatures very much below average (in the lowest 10% of historical observations since 1910).
Mean minimum temperatures were above to very much above average (in the highest 10% of historical observations) for most of Western Australia and Queensland and large parts of the Northern Territory. Small areas of the Pilbara and Gascoyne in Western Australia, Daly in the Northern Territory, around Darwin and on Cape York Peninsula in Queensland experienced their highest mean minimum temperatures on record for the wet season period.
Area-averaged minimum temperatures for November and December 2023 were around 1.5 °C above average, while for January and February 2024 they were the second-highest and the highest on record respectively, with the area-averaged anomaly for both months exceeding 1.60 °C. The March 2024 area-average minimum temperature of 1.76 °C above average was the third-highest on record. Most of Cape York Peninsula and parts of south-western Queensland extending into south-eastern Northern Territory and areas in the north of the Northern Territory recorded their highest March minimum temperatures on record. October 2023 and April 2024 were the only months with below average minimum temperatures across Northern Australia.
Water availability
A dry October 2023 saw below average root zone soil moisture (moisture in the top 100 cm of soil) in most areas of northern Australia. The majority of streamflow sites were at their historical average, but major storages such as Lake Argyle, Darwin River and Tinaroo Fall remained above 80% full.
Rainfall in November 2023 increased soil moisture in most areas, except tropical northern Queensland and parts of Western Australia.
During December 2023 streamflow improved across northern Australia. This was more pronounced in the north-eastern catchments, due to heavy rainfall associated with ex-tropical cyclone Jasper in mid-December. This resulted in widespread minor to moderate flooding in north-eastern catchments and the Gulf Country and Major flooding in the Daintree River and Murray River. The exception was the north-west coast of Western Australia, where below average rainfall dominated the season and soil moisture and streamflow remained below to very much below average throughout.
In January 2024, with the onset of the monsoon, a large number of locations in the Carpentaria Coast and Tanami-Timor Sea Coast drainage divisions in Queensland and the Northern Territory had above average to very much average streamflow. Widespread heavy rain resulted in flood warnings in some northern rivers such as Katherine River, Daly River, and Victoria River in the Northern Territory. The Victoria Highway closed, and some local communities were evacuated. This month also saw a number of storages at their full capacity and these storages remained full for the remainder of the wet season.
The wet conditions continued into February and March 2024. Major flood warnings were current in February for the Flinders River and Eyre Creek and numerous catchments were at flood watch across Queensland. By end of March, high rainfall totals across much of northern Australia increased soil moisture to above to very much above average particularly across catchments in central and western Northern Territory and north-west Western Australia.
At the end of the wet season period, the majority of the storages were full and most northern Australian rivers were flowing at above their historical average. However, the above average rainfall in April did not raise the streamflow across south-eastern areas in Queensland.
Atmosphere and oceans
Australia's climate has warmed on average by 1.50 ± 0.23 °C between 1910 when national records began and 2023, with most of the warming occurring since 1950. The warming in Australia is consistent with global trends, with the magnitude similar to the average across the world's land areas. Rainfall across northern Australia has increased during the northern wet season since the 1970s, with more high intensity and short duration rain events.
The record warmth in global sea surface temperatures (SSTs) since April 2023 was reflected in the waters around northern Australia. For the northern tropical region overall (defined as waters between 4°S and 22°S, and 94°E and 174°E), the 2023–24 wet season SSTs were the third-warmest on record since 1900–01, at 0.69 °C above the 1961–1990 average. Coral Sea SSTs were fourth-warmest on record for the wet season overall, including warmest on record in January, February and April 2024, and second-warmest on record in March.
El Niño was declared by the Bureau of Meteorology in September 2023 and the event continued for much of the wet season for northern Australia. The monthly NINO3.4 index reached a peak, in the ERSSTv5 SST dataset, of 2.27 °C above the 1961–1990 average in November 2023, before cooling slightly in December. El Niño atmospheric indicators of cloudiness and trade winds started returning to ENSO-neutral (reflecting neither El Niño or La Niña) values from December, while sea surface temperatures remained above El Niño thresholds and slowly returned to a neutral state of the El Niño–Southern Oscillation (ENSO) in mid-April 2024
Consistent with an active El Niño, the Southern Oscillation Index (SOI) was negative in the early part of the wet season. 30-day average SOI values were below -7.0 from October to early December, indicating relatively high surface pressure over northern Australia. As El Niño weakened from December 2023 onwards, SOI values were mostly ENSO-neutral, with some fluctuations due to transient tropical systems over northern Australia or Tahiti.
The Indian Ocean Dipole (IOD) was in a positive phase at the start of the wet season and the weekly IOD index peaked in the Bureau weekly SST dataset at +1.92 °C in the week ending 15 October 2023. This was the second-highest peak on record (with the dataset starting in July 2001) behind only 2019, which saw a peak of +2.15 °C. Due to the strength of the event, the decay was later than usual. The positive IOD eased through December 2023 as the SST gradient weakened, with the IOD index returning to neutral values by the end of January 2024.
The Madden–Julian Oscillation (MJO) modulates rainfall patterns and tropical cyclone potential in the region on weekly to monthly timescales during the northern wet season. The MJO was not observed near Australian longitudes at significant strength during October and November 2023. A moderate to strong MJO pulse entered the Maritime Continent region at the start of December and returned to this region for parts of January, March and April 2024, likely contributing to wetter conditions across northern Australia during these months.
The peak of local MJO activity in January 2024 likely contributed to the start of the first active monsoon over northern Australia. At Darwin, monsoon onset occurred on 10 January 2024. This was around two weeks later than the typical monsoon onset date at Darwin in late-December. This was likely due to the active El Niño and the positive IOD, which can decrease monsoon activity in the northern Australian region.
Tropical cyclones
- For the Australian tropical cyclone region, as defined for the Tropical Cyclone Outlook, there were 8 tropical cyclones (Jasper, Kirrily, Anggrek, Lincoln, Neville, Megan, Olga and Paul) that formed during the northern wet season.
- The long-term average (since 1969–70) number of tropical cyclones in the Australian region is 11, while in recent decades (since 2000–01) the average is 9.
- Four tropical cyclones (Jasper, Kirrily, Lincoln and Megan) made landfall on the Australian mainland, which is equal to the long-term average. Jasper and Kirrily made landfall in north Queensland while Lincoln and Megan developed in the Gulf of Carpentaria and made landfall on the south-west Gulf of Carpentaria coast of the Northern Territory. The last time the Queensland east coast had two tropical cyclones that reached Category 2 or higher was during the 2014–15 season (Nathan and Marcia).
- Six tropical cyclones reached severe strength (at least category 3) in the Australian region and two of these, Jasper and Olga, reached category 5.
- Three tropical cyclones (Anggrek, Neville and Olga) developed in the western region and remained offshore. The last season when there were no tropical cyclone crossings in the western region was 2018–19.
- There were an additional 3 observed tropical lows 03U, 06U and 10U in the Australian region during the October 2023 to April 2024 period.
Severe Tropical Cyclone Jasper
- Tropical low 02U formed in the Solomon Sea on 2 December 2023 and developed into a Category 1 system as Tropical Cyclone Jasper on 5 December.
- Jasper continued to intensify while tracking west and south from the Solomon Sea into the Coral Sea and peaking as a Category 5 cyclone (severe) on 8 December before weakening to a Category 1 system on 11 December as it approached the north Queensland coast.
- Tropical Cyclone Jasper intensified to a Category 2 cyclone on 13 December before turning west and making landfall in the evening on Queensland's north tropical coast near the community of Wujal Wujal, 120 km north-west of Cairns.
- The cyclone weakened to a tropical low as it moved inland and stalled over the Cape York Peninsula for several days before dissipating on 17 December.
- The tropical low produced significant rainfall with daily rainfall totals from 13 to 18 December between 100 and 600 mm, causing significant and widespread impacts including flooding, mass evacuation of communities, landslides and road closures.
- Many sites set daily December or annual daily rainfall records, such as Cape Tribulation Store which recorded 861.2 mm in the 24 hours to 9 am on 18 December. This is the third-highest daily rainfall (in the 24 hours to 9 am) total ever measured by a Bureau rainguage anywhere in Australia.
- Many sites across northern Queensland recorded more than 1000 mm of rainfall over the 5-day period. Three stations between Kuranda and the Daintree observed 5-day (14–18 December) rainfall totals in excess of 2000 mm: Black Mountain TM 2166 mm, Bairds TM 2118 mm and Myola Alert 2025 mm.
- Severe Tropical Cyclone Jasper was the first tropical cyclone in the Australian region for the 2023-24 season and the earliest to form in the Coral Sea in an El Niño year.
Severe Tropical Cyclone Anggrek
- Tropical low 04U developed in the Indian Ocean on 12 January 2024, about 500 km north-west of the Cocos (Keeling) Islands and was named Tropical Cyclone Anggrek by Jakarta TCWC on 15 January.
- Tropical Cyclone Anggrek then moved south into the Australian Area of Responsibility on 18 January. Anggrek reached Category 2 intensity on 19 January before weakening temporarily below tropical cyclone intensity on 22 January.
- Anggrek re-intensified on 23 January, whilst moving south-west to peak at category 3 intensity (severe) on 24 January and the following day moved into RSMC La Reunion Area of Responsibility.
- Tropical Cyclone Anggrek did not impact the Australian mainland.
Severe Tropical Cyclone Kirrily
- Tropical Low 05U formed in the central Coral Sea on 17 January with the arrival of the monsoon trough. The low developed into Tropical Cyclone Kirrily on 24 January and tracked west southwest towards the north Queensland coast.
- Tropical Cyclone Kirrily intensified to severe category 3 strength in the afternoon of 25 January before weakening to category 2 intensity as it crossed the coast that night near Balgal Beach, Rollingstone.
- Kirrily quickly weakened below tropical cyclone intensity and slowly travelled across central and western Queensland from 26 to 31 January, whilst producing daily moderate to heavy rainfall totals up to 100 mm with isolated falls greater than 200 mm.
- On 1 February, the low moved north and reached the southern Gulf of Carpentaria and generated strong wind gusts of 102 km/h at Mornington Island, the equal highest wind gust ever recorded at the site.
- Heavy rainfall continued to be associated with the low as the system moved south over land from 2 February travelling south near the Queensland/Northern Territory border and eventually into New South Wales on 5 February before merging with an existing trough on 6 February.
Tropical Cyclone Lincoln
- Tropical low 07U formed in the western Gulf of Carpentaria on 14 February and developed into Tropical Cyclone Lincoln on 16 February in the southern Gulf of Carpentaria. Lincoln made landfall the same afternoon in remote Northern Territory between Port McArthur and the Queensland border.
- Lincoln was downgraded to a tropical low several hours after landfall, and tracked west southwest across central Northern Territory and reached the Kimberley coast in Western Australia on 20 February. The low was associated with widespread heavy rainfall along its path, with multi-day rainfall totals (16 to 22 February) between 50 to 100 mm and some areas receiving over 200 mm, resulting in flooding and isolating communities due to road closures.
- The low moved off the west Kimberley coast on 21 February and remained as a tropical low over waters north of the Pilbara coast, tracking south-west off the coast of Western Australia, and turning south on 24 February eventually crossing the Gascoyne coast north of Carnarvon. The low moved south-east through Western Australia bringing daily rainfall totals of 10 to 50 mm with isolated totals of 50 to 100 mm along the Gascoyne coast in the 24 hours to 9 am on 25 February.
- Lincoln was a long-lived system, lasting 12 days, although it was only briefly at tropical cyclone strength.
Severe Tropical Cyclone Neville
- Tropical low 08U formed in the Indian Ocean on 7 March, north-west of the Cocos (Keeling) Islands. The low passed close to Cocos (Keeling) Islands and Christmas Island from 10 and 12 March, resulting in some wind damage at Cocos (Keeling) Islands, and generating high daily rainfall totals, strong wind gusts and significant swells at Christmas Island.
- The slow moving low progressed towards the Pilbara coast off Western Australia, then remained slow moving for several days and moved south and south-west before moving west and intensifying into Tropical Cyclone Neville (category 2) on 20 March, 400 km north offshore of Exmouth.
- Neville developed into category 4 intensity on the 22 March while tracking west away from the Australian mainland and continued to move westwards before turning south-west and weaking to a tropical low near the western boundary of the Australian region (90°E) on 24 March.
- Tropical Cyclone Neville did not impact the Australian mainland.
Severe Tropical Cyclone Megan
- Tropical low 09U formed near the Tiwi Islands, north of Darwin on 13 March, travelling east close to the Top End coast while generating high to locally intense daily rainfall totals.
- The low moved into the Gulf of Carpentaria developing into Tropical Cyclone Megan on 16 March. Megan tracked south intensifying into a severe tropical cyclone (category 3) in the morning of 17 March and peaking at category 4 intensity overnight. Megan weakened slightly before making landfall on the afternoon of 18 March as a category 3 system on the southwest Gulf of Carpentaria coast, south-east of Port McArthur.
- Megan was downgraded to a tropical low in the early hours of 19 March and tracked south-west then west across the interior of the Northern Territory towards Western Australia, bringing widespread rainfall.
- Megan was associated with damaging wind gusts and widespread and locally heavy falls around the south-west Gulf of Carpentaria. Centre Island (Northern Territory) recorded a maximum wind gust of 170 km/h on 18 March, the second-highest wind gust on record for March at this station, behind 220 km/hr on 24 March 1985. At Groote Eylandt gale-force winds late on 16 March caused significant damage to vegetation and the wharf was badly damaged as the Manganese bulk carrier MV Anikitos was pushed against it.
- Several sites also recorded their highest daily March rainfall on record, including Groote Eylandt Airport (Northern Territory) recorded 431.0 mm in the 24 hours to 9 am on 17 April and a record 2-day rainfall total of 680.4 mm (16-17 March).
- Several communities around the Gulf of Carpentaria experienced flooding, and the McArthur River at Borroloola reached major flood level leading to the evacuation of the local community. Many roads were closed and damaged near the path of the system further inland.
Severe Tropical Cyclone Olga
- Tropical low 11U formed south of Indonesia on 4 April and moved south developing into Tropical Cyclone Olga on 6 April.
- Olga travelled south-west away from the mainland and rapidly developed to peak at intensity category 5 intensity on 8 April. Olga then weakened over several days to a tropical low as it continued to move south-west parallel to the Pilbara coastline.
- Despite weakening Olga disrupted offshore oil and gas activities over the Northwest Shelf region. Some island locations recorded periods of gales but there were no gales recorded on mainland Australia.
Tropical Cyclone Paul
- Tropical low 09U developed close to Papua New Guinea on 9 April, moved south into the north-east Coral Sea becoming a tropical cyclone on 10 April and peaking at Category 2 intensity before weakening abruptly on 11 April.
- Tropical cyclone Paul was a short-lived tropical cyclone that caused no known impacts.
Related information
- Area-average data and time series charts for the northern wet season period
- Rainfall maps for the 7-months periods ending April
- Wet season climate summary for Northern Territory
About the data
All values in this statement were compiled from data available as of 15 May 2024. Subsequent quality control and the availability of additional data may result in minor changes to final values.
The use of current and historical climate information allows for comparison of climate impacts from one year to the next and aligns with other reporting processes that occur over northern wet season periods.
This statement was prepared using the following sources:
- Rainfall maps from the Australian Gridded Climate Dataset (AGCD) analyses.
- Temperature maps from the Australia Water Availability Project (AWAP) analyses.
- Area-average time series for the northern wet season are calculated from the homogenised Australian temperature dataset (ACORN-SAT) and AGCD monthly rainfall.
- Root-zone soil moisture from Australian Water Resources Assessment Landscape model (AWRA-L) 7.0 analyses.
- Water storage information and the Murray-Darling Basin Information Portal.
- Sea surface temperature from the ERSSTv5 dataset.
- Tropical Cyclone information from tropical cyclone reports.
Unless otherwise noted, all maps, graphs and diagrams in this page are licensed under the Creative Commons Attribution 4.0 International Licence
