Issued

Key facts for January to October

  • Above-average Australian rainfall 428.4 mm (48.1 mm above the 1961–1990 average)
  • High rainfall from May to October 2016 (wettest six months to October on record)
  • Strong negative Indian Ocean Dipole driver of heavy cool season rain
  • Australian mean temperature fourth warmest on record with an anomaly of +0.92 °C
  • Record warm ocean conditions with an Australian region anomaly of +0.80 °C

Australia has experienced a wide range of weather extremes during 2016, driven by a variety of climate influences. Record-high Australian land and sea surface temperatures (SSTs) and below-average rainfall featured during the first four months of the year, followed by record-high rainfall from May to October. The high rainfall and cloud cover saw temperatures cool over the continent during August to October, while SSTs remained much above average everywhere except near the southwest coast.

The year started under the influence of the 2015–16 El Niño, being one of the strongest events of the last century as measured by central Pacific Ocean SSTs. This event started to break down in early 2016, before ending in May. The Pacific remained El Niño–Southern Oscillation neutral (neither El Niño or La Niña) from June to November, though a number of climate indicators have approached La Niña thresholds in spring.

A strong negative phase of the Indian Ocean Dipole became apparent in May, as warmer-than-normal SSTs developed across the eastern Indian Ocean and cooler-than-normal temperatures developed further west. The shift from a "dry/warm" El Niño pattern to a "wet/cool" negative Indian Ocean Dipole pattern during El Niño’s breakdown largely explains the shifts in Australia’s climate as the year progressed.

A number of severe weather events which had climate-scale impacts occurred during 2016. Extreme rainfall impacted northern and eastern Tasmania in late January 2016, removing short-term rainfall deficiencies in these regions. During early June an extensive upper-level trough tracking south from Queensland, and an East Coast Low complex in the Tasman Sea, brought heavy rainfall that affected much of Australia’s east coast and Tasmania. In late September, an intense low pressure system crossed South Australia, bringing strong winds and locally heavy rainfall totals. High sea levels and damaging waves were a feature of coastal lows during the year, including major damage in South Australia in May and September, and on the east coast during June.

Australia’s rainfall; a year of contrasts

Rainfall deciles for January to October 2016
Rainfall deciles for January to October 2016, showing widespread above average falls

The first four months of 2016 were particularly dry across much of coastal northern Australia, resulting in the driest northern wet season in more than 20 years. The decline of El Niño and the shift to a negative Indian Ocean Dipole resulted in a remarkable transition from dry to wet conditions across Australia. April was Australia’s ninth driest on record, while May came in as the sixth wettest on record, followed by the second wettest June and then the second wettest September. Each of the four, five and six month periods starting May (i.e., May to August, May to September and May to October) were Australia’s wettest on record, providing relief from dry conditions which were widespread earlier in the year. Tasmania, which was suffering badly from drought conditions associated with a record-dry spring 2015 and dry start to 2016, had its wettest May to October on record, and has had its second-wettest January to October on record. Victoria and South Australia each had their sixth wettest January to October period on record.

The heavy rainfalls substantially eased long-term droughts which had been in place since 2012 in much of inland Queensland, and in western Victoria and southeast South Australia. For example, at Longreach 402.6 millimetres of rain fell over the five months from May to September some five times the long-term average for this period (85 mm). In June alone, Longreach recorded 173.8 mm, greater than the 168.0 mm it received for all of 2014 and the 165.4 mm it received for all of 2015. This is even more remarkable when considering that May to September is normally the driest time of the year in Longreach.

Temperature across Australia during 2016

The El Niño, in combination with the background warming trend in the ocean, led to record-warm summer SSTs around much of Australia, including in the Coral Sea where widespread coral bleaching was observed and to Australia’s northwest. Year-to-date SSTs for the Australian region have been 0.15 °C warmer than the previous January–October record (+0.65 °C set in 1998), with the SST anomalies in the Coral Sea 0.24 °C higher than the previous record (+0.61 °C in 2010). SSTs around Australia have warmed by nearly 1 °C since 1900 and this year adds to this long-term warming trend.

SST deciles for January-October 2016
Sea surface temperature deciles for January to October showing widespread above average to record warm conditions around Australia, using gridded data derived from NOAA’s ERSST version 4 dataset

Land temperatures started the year well above average, before cooler conditions became established with the high rainfall. A significant heatwave affected much of Australia during late February and the first half of March, the latter period contributed to Australia’s warmest March and warmest autumn on record. Generally above-average mean temperatures persisted throughout most of winter for all but southern and western parts of Australia. With wetter conditions, spring has seen cooler-than-average temperatures nationally with a September mean temperature anomaly of −0.04 °C and October anomaly of −0.50 °C, although the far north has remained warm.

Mean temperature deciles for January to October 2016
Mean temperature deciles for January to October 2016, showing above average to record warm conditions for most areas, apart from the southwest

For Australia, the year-to-date (January to October 2016) and the 12 month running mean temperatures (November 2015 to October 2016) are currently fourth and second warmest on record with anomalies of +0.92 °C and +1.01 °C, respectively. The current climate outlook suggests that above average temperatures are likely to return during November and December, suggesting a warm end to the year.