Climate outlook for January to April

Long-range forecast overview

• January to March rainfall is likely to be below median across much of the north and west of Australia.
• January to March maximum and minimum temperatures are very likely to be above median for most of Australia.
• January to March maximum and minimum temperatures are at least 2.5 times more likely than normal to be unusually high for much of Australia. Unusually high temperatures are defined as the warmest 20% of January to March periods from 1981 to 2018.
• The long-range forecast is influenced by several factors, including the active El Niño, an easing positive Indian Ocean Dipole event and record warm oceans globally. For more detail, see the Climate Influences section.

Drier than median January to March outlook for northern and western Australia

• For January, rainfall is likely to very likely (60% to greater than 80% chance) to be below median for most of northern Australia and western WA. Above median rainfall is likely (60 to 80% chance) for regions extending from south-east Queensland into northern NSW.
• For January to March, below median rainfall is likely to very likely (60% to greater than 80% chance) for most of the tropics, most of WA, scattered parts of SA, and the south-west Queensland.
• Unusually low rainfall for January to March is at least twice as likely for parts of western and northern WA. Unusually low rainfall is defined as the driest 20% of January to March periods from 1981 to 2018.
• Past accuracy of January to March long-range forecasts for the chance of above median rainfall is moderate to high for most of Australia, decreasing to low to very low for small areas in the central NT, extending into northern WA, as well as western SA and a small part of the NSW east coast.

Warmer January to March days and nights likely for most of Australia

• For January, above median maximum temperatures are likely to very likely (60% to greater than 80% chance) for most of Australia, excluding south-eastern SA and much of the south-east of the mainland.
• For January to March, above median maximum temperatures are very likely (greater than 80% chance) for almost all of Australia, and likely (60 to 80% chance) across southern NSW and southern SA. There are roughly equal chances of above or below median maximum temperatures over eastern Victoria and coastal South Australia.
• For January, and January to March, above median minimum temperatures are likely to very likely (60% to greater than 80% chance) for most of Australia except southern SA and western WA.
• For January to March, most of Australia is at least 2 times more likely than normal to experience unusually high maximum temperatures. The chance of unusually high maximum temperatures increases to greater than 4 times more likely than normal for parts of north-western and interior WA, and the far north of both the NT and Queensland. Unusually high temperatures equate to the warmest 20% of January to March periods from 1981 to 2018.
• For January to March, most of Australia is at least 2 times more likely than normal to experience unusually high minimum temperatures. The chance of unusually high minimum temperatures increases to greater than 4 times more likely than normal for most of northern Australia extending into the southern interior of WA and north-eastern NSW. Unusually high temperatures equate to the warmest 20% of January to March periods from 1981 to 2018.
• Past accuracy of the January to March long-range forecast for chance of above median maximum temperatures has been high to very high across Australia. Past accuracy of the January to March long-range forecast for chance of above median minimum temperatures.

Climate influences

The long-range forecast reflects known impacts from several significant climate drivers:

• The Southern Annular Mode (SAM) is likely to remain positive for at least the next two to three weeks. During summer, a positive SAM has historically increased the chance of above average rainfall for parts of eastern NSW, south-eastern Queensland, eastern Victoria, and north-east Tasmania, but increases the chance of below average rainfall for western Tasmania. This increased likelihood of rain due to the positive SAM is from westerly winds shifting further south, increasing onshore flow over south-east Australia.
• The El Niño event continues in the tropical Pacific—the typical drying influence of El Niño on Australia's climate usually reduces during summer, especially in the east; however, below median rainfall is still often observed in north-east Australia. As observed this year and in past El Niño years, high-impact rainfall events can occur during El Niño years, particularly during October to April when severe storm frequency peaks, even when the season is dry overall.
• A positive Indian Ocean Dipole (IOD) event remains active but is steadily weakening. IOD events typically breakdown as the monsoon trough shifts south into the southern hemisphere, typically at the end of spring. The breakdown this year has been later than usual. Model forecasts suggest the positive IOD is likely to continue to ease over the coming weeks, with the majority of models indicating the IOD index will fall below +0.4 °C in January.
• Global warming – global sea surface temperatures (SSTs) were highest on record for their respective months during April to November. Forecast unusually warm sea surface temperatures (SSTs) in the Tasman Sea may also be contributing to a chance of above median summer rainfall over parts of Australia.

The Bureau's climate model simulates the physics of atmospheric, oceanic, ice, and land surface processes and uses millions of observations from satellites as well as in-situ instrumentation on land and at sea. These simulations enable the model to account for the influence of climate change and natural climate drivers like ENSO, IOD, the Madden–Julian Oscillation (MJO) and SAM in its long-range forecasts.