Climate outlook for October to January
Climate outlook overview
- Rainfall is likely to be below average across most of the country for the remainder of 2019 and early 2020. However, for parts of northwest WA, there are slightly increased chances of above average rainfall for October to December.
- Daytime temperatures are very likely to be above average over virtually all of Australia during the October to January period.
- Nights are likely to be cooler than average across parts of the southeast and north during October to December, with warmer nights likely elsewhere.
- A positive Indian Ocean Dipole (IOD) remains the major influence on Australian climate over the coming months. A prolonged negative SAM (Southern Annular Mode) is also forecast, which at this time of the year is likely to enhance the drier signal across parts of eastern Australia.
High chances of drier October and November for most
- Rainfall is likely to be below average across most of the country during October to January. However, for northwest WA, there are slightly increased chances of above average rainfall through the October to December period.
- For the month of October, most of the country is likely to be drier than average. Large parts of the eastern two-thirds of the country are very likely to be drier than average (greater than 80% chance). This pattern continues into November, with most areas of Australia likely to be drier, except northern WA and western Tasmania.
Warmer end to the year very likely
- Daytime temperatures are very likely to be warmer than average for virtually all of Australia for the remainder of 2019 and early 2020.
- Nights are likely to be cooler than average in parts of the southeast and tropical north during October to December, with other areas likely to have warmer than average nights.
- The positive Indian Ocean Dipole (IOD) is forecast to continue until early summer, and is the main influence driving warmer and drier conditions across large parts of Australia.
- IOD events typically decay towards the end of the year, having little influence on Australian climate from December to April, meaning its contribution to the drier outlook should start to reduce in early summer.
- A prolonged period of negative Southern Annular Mode (SAM) is forecast by the Bureau's climate model during October and November. This is largely due to a sudden warming of the stratosphere over Antarctica.
- A negative SAM in the spring months often brings drier than average conditions to parts of eastern mainland Australia by reducing onshore flow, but also brings wetter than average conditions to western Tasmania.
- Forecast warmer than average sea surface temperatures off the northern WA coast are likely contributing towards the increased chances of above average rainfall for northern WA in October to December. Similarly, cooler than average waters are forecast further east, over northern Australia. These cooler waters are likely contributing towards the drier forecast across much of this region for October to December, as well as the cooler nights.
- The El Niño–Southern Oscillation (ENSO) is expected to remain neutral for the remainder of 2019.
- In addition to the natural drivers such as ENSO and the IOD, Australian climate patterns are being influenced by the long-term increasing trend in global air and ocean temperatures.
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