Issued

Introduction

Although 2023 is not yet over, this summary of Australia's climate and water from 1 January to 30 November 2023 provides an early indication of Australia's national annual mean temperature, area-averaged rainfall, and status of water resources for the year.

Summary

  • National mean temperature for January to November 2023 was 0.92 °C above the 1961–1990 average.
  • 2023 is on track to be one of Australia's warmest 15 years since records began in 1910 and tracking warmer than the previous 2 years.
  • Temperatures for January to November were above to very much above average for southern and central Australia, northern Queensland and the Top End of the Northern Territory, but below average for central parts of the Northern Territory and adjacent areas of inland Western Australia.
  • For January to November, national rainfall was close to the 1961–1990 climatological average of 416.4 mm.
  • January to November rainfall was above average for much of northern Australia, but below average for much of the south-eastern quarter of Queensland, and large parts of New South Wales, Victoria, Tasmania, South Australia and southern Western Australia.
  • It was the driest September on record and one of the driest months overall since the national dataset began in 1900.
  • Low to severe intensity heatwaves affected parts of Queensland, Northern Territory, South Australia and Western Australia between October to November.
  • For January to November, surface water storages decreased in the southern and eastern parts of the country compared to the start of the year.

What has the temperature been like?

For Australia as a whole, the mean temperature for January to November was 0.92 °C above the 1961–1990 average.

Australia's maximum temperature for January to November was 1.29 °C above average and ninth warmest on record for the January to November periods from 1961–1990. The national, area-averaged minimum temperature for January to November was 0.55°C warmer than the long-term average.

The mean temperature for January to November was above average (warmest 30% of all years since 1910) for southern and central Australia, northern Queensland, the Top End of the Northern Territory and a small area of the north- west coast of Western Australia. Cooler than average temperatures (coolest 30% of all years since 1910) were recorded in this period for central Northern Territory and adjacent areas of inland Western Australia.

Between January and April, temperatures were cooler than average across northern Australia, due to monsoonal activity and extensive cloud cover. Several low-to-severe intensity heatwaves affected many areas of Australia from February through to March.

In May, the national mean temperature was 1.10 °C below the 1961–1990 average, the lowest since 2011.

It was the warmest winter on record (since 1910) nationally, with a mean temperature 1.53 °C above the 1961–1990 average. The mean national temperature for June, July and August were among the ten warmest on record for the respective months, and September was the second warmest on record. Persistent high pressure over Australia throughout July to September contributed to the warm conditions.

Warm temperatures persisted into October and November, with frequent low-to-severe intensity heatwaves affecting areas of the Northern Territory, Queensland, South Australia and Western Australia.

Mean temperature deciles for January to November 2023
Mean temperature deciles for January to November 2023. Deciles are calculated by ranking past data for January to November periods from 1910 to 2023 and placing rankings into 10 equal and consecutive bins. Map shows the 10% bin (decile) that contain the 2023 values.
Maximum temperature deciles for January to November 2023
Maximum temperature deciles for January to November 2023, based on all years 1910 to 2023.
Minimum temperature deciles for January to November 2023
Minimum temperature deciles for January to November 2023, based on all years 1910 to 2023.

Where has it rained?

For Australia as a whole, January to November rainfall was close to the 1961–1990 average. January to November rainfall was above average for much of northern Australia, and very much above average (in the highest 10% of historical observations) for parts of northern Western Australia, central Northern Territory, and northern and north-western Queensland. Area-averaged rainfall over northern Australia (north of 26°S) for January to November was 553.8 mm, 21% above the 1961–1990 average and the highest since 2011.

Rainfall for January to November was below average for much of the south-eastern quarter of Queensland and large parts of New South Wales, Victoria, Tasmania, South Australia, and southern Western Australia. Averaged across southern Australia (south of 26°S), rainfall for January to November was 273.1 mm, 24% below the 1961–1990 average.

In January, heavy rainfall and thunderstorms associated with ex–Tropical Cyclone Ellie and monsoonal rain affected many parts on northern Australia, resulting in flooding of major river systems in the Kimberly region of Western Australia, central parts of the Northern Territory and areas of northern Queensland. A monsoon trough and tropical low brought heavy rainfall and thunderstorms to the northern interior of the Northern Territory and north-western Queensland during the last week of February through to early March. In mid-April, heavy rainfall was associated with Tropical Cyclone Ilsa which made landfall on the Pilbara coast of Western Australia and weakened as it traversed south-eastwards inland towards central Australia.

After a wet January to April nationwide, May, August, September and October were all in the top ten driest for their respective months since 1900. For Australia as a whole, August–October 2023 was the driest 3-month period on record since 1900. September was also one of the driest months overall since the national dataset began in 1900. Conditions from May to October were dominated by high pressure systems over much of the country that brought settled weather and cloudless skies, with fewer rain-bearing systems and cold fronts affecting southern Australia.

In November after three very dry months, rainfall totals for November were above average for most of Australia as large areas of central, northern and eastern Australia were impacted by widespread and at times heavy rainfall and isolated thunderstorms.

Rainfall deciles for January to November 2023
Rainfall deciles for January to November 2023, based on all years 1900 to 2023.

What does this mean for water storages?

Due to dry catchments and low streamflow conditions across much of the southern parts of the country, water level in many storages decreased during the first 11 months of 2023. Despite, total surface water storage volume remained high and finished November at 75.3% of its accessible capacity.

At the end of November, surface water storages supplying major capital cities remained high (over 80.0% of their accessible capacity), except in Brisbane (66.3%), Adelaide (68.7%) and Perth (49.1%). With low surface water storages, Perth's water supply is more reliant on desalination and groundwater as the alternative sources of water supply for the past several years.

See caption
Major storage levels across Australia at the end of November.

At the beginning of the year, major water storages in the Murray–Darling Basin were almost at their full capacity. However, due to combined dry catchment condition with irrigation season demand in the later part of the year, storage volume in the Murray-Darling Basin declined and reached to 88.7% by end of November.

In northern Australia, above to very much above average rainfall during the wet season (October 2022–April 2023) resulted in high soil moisture and inflows to Lake Argyle, the largest water supply storage in Australia. In March, storage volume in Lake Argyle reached 121.4% of its accessible capacity, the highest since 2017.

In south-east Queensland, the Nogoa Mackenzie rural system remained below 50% of its accessible capacity throughout the year, finishing at 31.4% at the end of November. Wivenhoe, the largest storage in south-east Queensland, started the year at 79.2% of its accessible capacity, but its water storage decreased to 63.4% at the end of November.

What is the outlook for the rest of the year?

The long-range forecast, issued on 30 November, indicates that December rainfall is likely (60 to 80% chance) to be below median for much of northern Australia, parts of southern Western Australia and South Australia, and small parts of south-east Australia. Large parts of inland Australia have a near equal chance of above or below median rainfall. However, if above average rainfall occurs, it is unlikely to be widespread.

For December, above median maximum temperatures are likely to very likely (60% to greater than 80% chance) for most of Australia, excluding some eastern inland regions. Above median minimum temperatures are likely to very likely (60% to greater than 80% chance) for most of Australia except western parts of the Pilbara and Gascoyne districts in Western Australia, and central coastal regions of Queensland.

Considering the outlook for December with January to November observations, 2023 is very likely to be among the top 15 warmest years on record (since 1910) for Australia as a whole and the warmest since 2020. If the mean temperature in December is inside the top 10 warmest December's on record, it is likely for 2023 to also be among the top 10 warmest years on record.

The area-averaged total rainfall for January to November is close to average and 2023 is also likely to remain close to average overall.

What has been driving weather in 2023?

El Niño and positive Indian Ocean Dipole combine for a dry and warm end to the year

After three consecutive years of La Niña (from 2020–21 to 2022–23), oceanic and atmospheric indicators weakened towards neutral El Niño–Southern Oscillation (ENSO) values during summer 2022–23.

In early autumn, the tropical Pacific Ocean began showing early signs of a developing El Niño. Sea surface temperatures in the central tropical Pacific Ocean continued to strengthen and by June, exceeded El Niño thresholds. However, it was not until early spring that a clear atmospheric signal emerged in response to sea surface temperatures, and an El Niño event was established.

A positive Indian Ocean Dipole (IOD) pattern emerged in mid-August, with a gradient of temperature anomalies developing across the Indian Ocean. The IOD index exceeded and sustained positive IOD thresholds (+0.40 °C) from mid-August, with values strengthening, then peaking at +1.92 °C in the week ending 15 October. The weekly IOD index values for this event have been the second-highest since the Bureau sea surface temperatures dataset began in 2001, behind the strong positive IOD event of 2019.

The concurrent positive IOD and El Niño events likely contributed to the above average temperatures and below average rainfall across southern and eastern Australia during the second half of 2023. The observed patterns of temperature and rainfall were consistent with historical, concurrent positive IOD and El Niño events.

The positive IOD will likely ease in December, and the current El Niño is expected to continue into the early southern hemisphere autumn 2024.

Climate change continues to influence Australian climate. Australia's climate has warmed by 1.48 ± 0.23 °C since national records began in 1910, with an increase in extreme heat events and an increased likelihood of high intensity, short duration rainfall events as published in the Bureau's State of the Climate 2022.

Sea Ice

Antarctic sea ice is an important component of the Earth's climate and ecology, reflecting incoming solar radiation, influencing interactions between the ocean and atmosphere, contributing to the global ocean circulation, protecting ice-shelves from ocean processes, and providing a habitat for polar species.

Antarctic sea ice experiences large seasonal changes, with net summertime sea-ice extent being ~2–4 million km2 expanding to a wintertime extent of ~18–20 million km2. Based on large-scale satellite data since 1979, the last decade has seen quite a distinct rise in variability in sea-ice extent, with record high wintertime extents being observed in 2012–2014 followed swiftly by record low values observed since 2016. In 2023, net Antarctic sea ice extent was at record low levels or well below the long-term (1991–2020) average and sea ice had rapidly retreated, particularly across East Antarctica where Australia's bases are positioned. This is largely attributed to warmer than average subsurface Southern Ocean temperatures.

It is expected that summer 2023-24 sea ice conditions will be very much below average.

Antarctic sea-ice extent anomaly for 2023
Antarctic sea-ice extent anomaly for 2023

Global oceans

Record warm oceans globally was a key feature of 2023. Since April, averaged over 60°S to 60°N, monthly sea surface temperatures have been the warmest on record for their respective months, as well as being in the top 10 largest monthly anomalies on record. August was the warmest month on record, at 0.92 °C above the long-term (1961–1990) average.

Global temperature

In its provisional report on the State of the Global Climate in 2023, based on data for the first ten months of 2023, the World Meteorological Organization (WMO) reported that 2023 is likely to be the warmest year on record for the globe, with the past nine years (2015 to 2023) on track to be the nine warmest on record.

The report also states the global temperature for 2014–2023 (to October) is 1.19 ± 0.12 °C above the 1850–1900 average, the warmest decade on record.

Product code: IDCKGC7AR0

Climate