The strongest positive Indian Ocean Dipole (IOD) since 2001 is helping create dangerous drought conditions, the Bureau of Meteorology says.

Characterised by cooler waters to the northwest of Australia and warmer waters further west, a positive IOD usually brings below average winter and spring rainfall to southern and central Australia, and warmer days.

Australia is also facing a prolonged period of negative Southern Annular Mode (SAM), which is exacerbating the situation.

Largely due to a sudden warming of the stratosphere over Antarctica, a negative SAM brings drier than average conditions to eastern Australia.

The bureau’s latest outlook for October to December warns that the dry and warm start to spring is likely to continue to the end of the year, with increasing levels of drought, heatwaves and bushfire conditions.

“The month of October has a high chance of being drier than average for virtually the entire country, while October to December sees drier than average conditions very likely for most of southern and eastern Australia,” Senior Climatologist Andrew Watkins said.

“Days are very likely to remain warmer than average across Australia. This also means there is an increased chance of early heatwaves, and windy days will see very high fire danger.”

The bureau has activated its heatwave service, which uses maps to show heatwave location and severity.