Issued 2 December 2019, Updated
The year is not yet done, but with most of it behind us, we can look at what's happened so far, and how it might look once the year is complete. The temperature and rainfall rankings for 2019 could still change in the remaining weeks, but we can certainly say that almost the whole country has had a very warm and very dry year so far.
- Almost certain to be amongst the four warmest years on record for Australia
- Days especially warm
- Annual rainfall for Australia as a whole likely to be in the driest ten years on record
- Much of Australia affected by drought, especially severe in New South Wales and southern Queensland
- Flooding across northern Queensland and the Gulf Country between February and April, leading to a significant filling of Lake Eyre / Kati Thanda
- Significant heatwaves in January contributed to Australia's warmest summer on record
- Large bushfires affected Victoria and Tasmania between January and March
- Prolonged period of bushfires affecting southeast Queensland and northeastern New South Wales from September
How is the year shaping up?
2019 will rank amongst Australia's warmest and driest years on record.
Australia's mean temperature over January to November has been the highest on record for large areas of eastern and northern New South Wales, extending into southeastern Queensland, and for a large area extending from the Pilbara coast in Western Australia to northwest South Australia. January–November was the warmest on record for just over one quarter of the country, and very much warmer than average for the remainder outside of areas of western and northern Queensland.
The Bureau's climate outlooks indicate a strong likelihood of above-average temperatures for December 2019.
Based on this climate outlook and the behaviour of recent years, it's likely the final annual mean temperature will be between 1.3 °C and 1.4 °C above average. That puts the annual mean temperature for 2019 on track to be one of the four warmest years on record. Australia's January–November 2019 mean temperature was the second-warmest on record, at 1.36 °C above the 1961–1990 average.
Regardless of where 2019 does place in the final ranks, it will continue a run of very warm years. All of the years since 2013 have been amongst the ten warmest on record for Australia. Of the ten warmest years, only one (1998) occurred before 2005.
Persistent warmth during 2019 has been driven by the combination of the long-term warming trend and natural climate drivers including a long-lived positive Indian Ocean Dipole (IOD). The overall sea surface temperatures pattern in the Indian Ocean was generally consistent with a positive IOD from late May, and firmly in positive territory since August. During spring the IOD index reached the highest weekly values observed in the Bureau's dataset, which extends from 2001. The peak value, +2.15 °C for the week ending 13 October, was well above the previous record of +1.48 °C for the week ending 5 November 2006.
This very strong, positive IOD has contributed to very low rainfall across Australia. A positive IOD often results in below average winter–spring rainfall over southern and central Australia. It also typically means warmer than average winter–spring days for the southern two-thirds of Australia.
Given the positive IOD remains so strong, it is likely its influence could persist well into mid-summer. This is reflected in a continued dry outlook for most of Australia for December.
Sudden stratospheric warming also played a role in spring, when the stratosphere high above the South Pole began rapidly heating at the end of August. This shifted the belt of westerly winds over the Southern Ocean towards the equator, resulting in warmer than average spring temperatures and below average rainfall across large parts of eastern Australia.
Low rainfall also contributed to higher daytime temperatures over Australia during 2019, as dry soils reduce evaporation from the landscape, which would otherwise exert a cooling influence. Those same dry soils contributed to the relatively low night-time temperatures seen in winter across much of inland Australia.
Despite many areas seeing unusually cold nights during at least one month between May and November, the overall mean minimum temperature for the year so far has also been above average for most of the country.
Previous warm and dry years have often been associated with El Niño, but the tropical Pacific Ocean remained ENSO-neutral during 2019.
In addition to the influence of natural drivers, Australia's climate is increasingly influenced by global warming and natural variability takes place on top of this background trend. Australia has warmed by just over one degree since 1910, with most of the warming occurring since 1950.
A very dry year so far
Overall, 2019 to-date has been a very dry year for Australia. January–November rainfall has been the second-lowest on record for Australia as a whole (spanning 120 years), coming in behind only January–November 1902. For the year to date, rainfall has been below to very much below average over most of Australia except central to northern Queensland.
Rainfall for January–November was above average across parts of Queensland's northwest and northern tropics, mostly as a result of very much above average rainfall during the first quarter of the year.
The year commenced with significant rainfall deficiencies in place across large areas of eastern Australia, and low rainfall during the year has resulted in an increase in the severity of rainfall deficiencies and an expansion of the area affected (see Special Climate Statement Drought conditions in eastern Australia and impact on water resources in the Murray–Darling Basin).
As well as the significant deficiencies affecting New South Wales, southern Queensland, eastern Victoria, and eastern South Australia, rainfall deficiencies intensified throughout the year in Western Australia — including across the South West Land Division.
Several active tropical systems, including severe tropical cyclone Trevor, brought above average rainfall to parts of northern and western Queensland during the first months of 2019. Significant flooding resulted in and around Townsville during late January to early February. In the Gulf Country and western Queensland extensive and long-lived flooding lasted from February into April, spread at its peak across an area some 70 km wide and an estimated 15 000 square kilometres in total area. Further information on the flooding can be found in Special Climate Statement An extended period of heavy rainfall and flooding in tropical Queensland. Floodwaters from these events eventually made their way to Lake Eyre / Kati Thanda in South Australia, for the most significant filling event for Lake Eyre / Kati Thanda since 2010–11.
In Western Australia, severe tropical cyclone Veronica caused major flooding in the coastal Pilbara during March.
Although March and April were wetter than average for some parts of eastern Australia, April was very much drier than average for eastern New South Wales and most of Victoria.
For the remainder of the year rainfall was generally below average over large areas, with conditions turning especially dry from July onwards across continental southern Australia. July–November rainfall was the lowest on record for the southern half of Australia.
In addition to the very dry second half of the year, parts of Queensland and New South Wales have had significantly below average rainfall for several years. Extremely dry conditions and very much above average temperatures led to increased fire risk across New South Wales and Queensland during spring (see Special Climate Statement Severe fire weather conditions in southeast Queensland and northeast New South Wales in September 2019).
Widespread warmth throughout the year, and significant fires
Low rainfall has been accompanied by very high daytime temperatures. Maximum temperatures have been above, to very much above average for most of Australia for nearly every month so far this year, with minimum temperatures not far behind, despite being below average for some areas in the months from May.
Daytime maximum temperatures in particular have been very warm nationally. The mean maximum temperature for January–November was 1.90 °C above average, the highest on record for the 11-month period. The annual value is likely to be among the five warmest on record.
Minimum temperatures have also been warmer than average, at 0.83 °C above average for January–November, the seventh-highest on record for the period. While drought years have often seen cooler than average minimum temperatures in the past, the background warming trend (+1.4C °C since 1910) now means that minimum temperatures are more often above average, even in years of extremely low rainfall.
The year got off to a very warm start for much of the country, as prolonged stable and sunny conditions and a delayed onset of the monsoon in northern Australia led to a build up of heat. January was exceptionally warm, and was the hottest month on record for every State and Territory except South Australia and Western Australia. New South Wales broke its previous record by more than 2 °C. More details, including a summary of records, can be found in Special Climate Statement Widespread heatwaves during December 2018 and January 2019.
Widespread warm and dry conditions, on top of well below average rainfall over multiple months, contributed to significant fires during January in Gippsland in Victoria and across large areas of Tasmania. Though less extreme than during January, above average maximum temperatures persisted well into autumn, and along with a lack of rainfall contributed to further significant fires during February and early March.
Monthly mean minimum temperatures were very much below average for southwest Western Australia during May, with some stations having for their coldest May night on record during the middle of the month.
Monthly mean minimum temperatures were very much below average for southeastern Australia during August, and during September for parts of the mainland southeast and for large areas of the northern tropics. Frost events during the first half of September led to severe frost damage to crops in southwest Western Australia, and some areas of crop damage in southeast South Australia and western Victoria.
September, October, and November mean maximum temperatures were very much warmer than average over large parts of Australia. Several times over the three months, warm spells with high temperatures, very low humidity, and strong winds led to dangerous fire weather conditions. A large number of fires were active across southeastern Queensland and northeastern New South Wales in early September. Additional fires started as spring progressed, with significant fires across eastern New South Wales reaching as far south as the outskirts of Sydney. Dry lightning also led to fires in East Gippsland and northeast Victoria towards the end of November.
What about the globe as a whole?
For the globe as a whole, 2019 is on course to be the second or third warmest year on record, continuing the recent pattern of very warm years.
The World Meteorological Organization (WMO) issued its preliminary statement on the climate of 2019 on 3 December.
The last four years—2015, 2016, 2017, and 2018—were the four warmest on record, and although 2019 is unlikely to reach the record set in 2016, this year will almost certainly be in that top group.
All of the ten warmest years globally have occurred between 1998 and the present. Global mean temperatures have increased by over 1 °C since records began in 1850, and, according to information collated by the World Meteorological Organization (WMO), 1978 was the last time the global annual mean temperature was below the 1961–1990 average.