The Fast Break – Victoria

Seasonal climate risk information for Victoria

Volume 21 | Issue 9 | 23 September 2026

Rainfall has been less than average so far in September, with not much on the forecast to improve the situation by the end of the month. Subsequently, soil moisture has been decreasing, with some crops and pastures using more than 40% of a full profile in a 3-week period. East Gippsland remains drier than normal with no useful improvement to soil moisture.

Just maybe the El Niño might be starting to exert some influence, as pressure patterns took a turn for the worse. The subtropical ridge of high pressure has increased in strength and averaged a blocking position over the state, sending weather systems south. This is classic El Niño behaviour.

In the Pacific the ocean continued to warm and the cloud remained suppressed over northern Australia, with increased pressure at Darwin and stronger westerly winds in the western Pacific. Models predict the event to continue over summer and break down in autumn. Historically, summer El Niños have had variable rainfall but are usually warmer.

The Indian Ocean has had another attempt at being a positive Indian Ocean Dipole (+IOD). Stronger easterly winds around Java have made cooler water to upwell in the eastern part of the eastern IOD box. The Dipole Mode Index value is at a +IOD value due to the combination of warmer water off Africa and the cooler eastern IOD box. A large area with a of lack of cloud and higher pressure exists off Indonesia, but nothing is happening off Africa to suggest coupling. Currently, the winds off Indonesia have returned to normal, suggesting it’s not the real deal yet. Many models predict a weak +IOD-like ocean pattern to persist for spring.

The Southern Annular Mode has been negative, but at a time of the year where its behaviour leads to variable results. NOAA and BoM models are divergent as to whether it goes positive or negative in the next fortnight.

The Madden Julian Oscillation has been in no man’s land for the last 30 days and is predicted to stay that way for the next 30.

My assessment of 12 climate models for Victoria is split between neutral and likely drier and likely to be warmer for the next 3 months.

Soil moisture

Plant-available moisture decile 20 September 2026

The BoM Australian Water Outlook (AWO) plant-available soil moisture deciles for perennial pasture show that south of the Divide is ranked drier and north of the Divide is generally wetter-to-average.

Many probe values remain high, above 75%. Those that are between 50% and 75% have decreased from near-full values over the last 30 days.

No sites have increased in soil moisture over the last 30 days but some high-rainfall pastures remained wet at 100%. Of those pastures that decreased, the median loss was 15 percentage points. The crop sites decreased by 19 points.

In the last 30 days, the Stawell perennial pasture decreased by 44 percentage points from 100% to 56%. The Lima east pasture site decreased by 30 percentage points from 100% to 70%.

Soil moisture probe data can be accessed in real time at Agriculture Victoria’s soil moisture monitoring website.

Probes from Agriculture Victoria, Gecko Clan, Perennial Pasture Systems, Gippsland Agriculture Group and Murrayville Landcare networks.

Model distribution summary for the next 3 months

Predictions for October to December 2026 Victorian rainfall – the outlook from 12 global model forecasts is split between neutral and likely drier.

Predictions for October to December 2026 Victoria temperature – the outlook from 11 global model forecasts is for likely warmer.

Model distribution summary for the next 4 to 6 months

Predictions for January to March 2027 Victorian rainfall – the outlook from 9 global model forecasts is neutral.

Predictions for January to March 2027 Victorian temperature – the outlook from 9 global model forecasts is for likely warmer.

Model consensus forecast for the next 6 months

Current outlook (23 September 2026)

Previous outlook (29 August 2026)

Sea surface temperature (SST) anomalies

During September the eastern equatorial Pacific Ocean surface continued to warm, well above the threshold for El Niño. The relative oceanic values for NINO3 and NINO3.4 were +3.49 °C and +2.53 °C, respectively (20 September).

Seas to the north of Australia have cooled in the last fortnight, looking more El Niño-like and more closely matching the higher pressure and less cloud in this region.

The Indian Ocean has attempted to go into +IOD again. A burst of easterly wind off Java has again cooled the eastern half of the eastern IOD box. The Dipole Mode Index value is currently at +0.7 °C (20 September) at a +IOD-like value over +0.4 °C. While there is evidence of +IOD-like behaviour in the eastern box, there is no evidence for proper coupling with the western node of the Dipole.

Sea surface temperatures are the key to the world’s rainfall. For more information on how they are measured, maps created and how to read them, check out our eLearn.

National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch Daily 5 km SST Anomalies (Version 3.1) 21 September 2026.

Equatorial last 30-day subsea temperature anomalies

Average of 21 August to 15 September 2026

The Pacific Ocean equatorial subsurface temperatures show a large volume of much warmer than normal water, feeding the surface warming. A region of cooler water in the western Pacific is possibly the El Niño turn-off key, which will slowly propagate eastwards over coming months to nullify the warming.

The eastern Indian Ocean shows no pre-IOD-like patterns.

Southern Oscillation Index (SOI)

30-day moving SOI 20 September 2026

The SOI is the difference in air pressure between Tahiti and Darwin.

During September the SOI has remained at a strongly negative value, indicative of El Niño air pressure patterns around the equator. Currently at −19.9 (as of 20 September). Pressure at Tahiti has returned to normal after being slightly higher, which is why the SOI is falling again. Higher pressure to our tropical north makes it harder to bring tropical moisture down from that region.

© Copyright Commonwealth of Australia 2026. Bureau of Meteorology. Climatology period 1933–1992.

Dipole Mode Index (DMI)

Latest weekly value to 20 September 2026

The DMI is the difference between the temperature of the west and east boxes of the Indian Ocean monitored for the IOD.

The DMI has re-risen to a +IOD-like reading of +0.7 °C. This is due to the temperature in the east box being less than the temperature in the western box of ocean.

© Copyright Commonwealth of Australia 2026. Bureau of Meteorology.

Pacific Ocean surface wind anomalies

Operational data surface winds 30-day anomaly for Monday 24 August to Tuesday 22 September 2026

During September, westerly winds continued in the western Pacific, extending halfway across the Pacific. The winds remain further north of the equator than a textbook El Niño.

A burst of easterly wind off Java has reignited the Indian Ocean’s interest in a +IOD, but currently those winds have returned to normal.

World cloudiness anomalies

OLR anomalies: Average of 22 August to 21 September 2026

Cloud patterns at the junction of the Date Line and north of Australia are classic El Niño in appearance. Greater cloud emanating over the warm water in the western Pacific is balanced by a lack of cloud over PNG and Indonesia.

In the Indian Ocean an ‘eye’ of lack of cloud exists off Sumatra, which looks suspiciously like a +IOD pattern, but there is no corresponding increase in cloud off Africa.

Source: Bureau of Meteorology.

Southern Annular Mode (SAM)

AAO: observed and GFS forecasts. Observations 26 May to 22 September 2026

The Southern Annular Mode (SAM) or Antarctic Oscillation (AAO) spent the first half of September in negativity before going positive. A −SAM in spring has often had mixed rainfall results.

The NOAA and BoM models are divergent, with NOAA going negative and BoM going positive in the next fortnight.

Source: NOAA.

Madden–Julian Oscillation (MJO)

MJO phase diagram for 13 August to 21 September 2026

In the last month the MJO cloud band has been mainly inactive. It started in the Coral Sea at position 6 and then weakly tracked eastwards to finish at position 8 between Tonga and Africa, currently at a strength of 1.5.

Over the next 30 days the MJO is predicted to remain weak, reaching position 2 in the western Indian Ocean but in a very weak state.

The MJO is a cloud band travelling in an easterly direction just under the equator. It often takes around 40 days to complete a circumnavigation and can be a moisture source when it’s north of Australia at positions 5 and 6, particularly in winter and spring in Victoria.

Source: Bureau of Meteorology.

Air pressure

Operational data surface winds 30-day anomaly for Monday 24 August to Tuesday 22 September 2026

In the past 30 days the Sub Tropical Ridge of High Pressure (STR) started behaving more El Niño-like, positioning a stronger-than-normal blocking high more often over Victoria, chasing weather systems south. The latitude of the high is at a normal spring latitude, centred over Adelaide.

Source: BoM.

Air pressure anomalies

Operational data surface winds 30-day anomaly for Monday 24 August to Tuesday 22 September 2026

The Sub Tropical Ridge increased in pressure over September, putting pressure on passing weather systems southward. Historically pressure is higher over the country in El Niños. Higher pressure in northern Australia is decreasing the moisture feed from the north.

Pressure is normal at Tahiti but much higher at Darwin, which is why the SOI is strongly negative.

Source: BoM.

Definitions

Read a list of climate acronyms and explanations.

Modelled climate and ocean predictions for Victoria from September 2026-run models

Twelve climate models show their predictions for the next 6 months for the Pacific Ocean, Indian Ocean, rainfall and temperature for Victoria.

View a colour-coded version of these tables [MS Word Document - 77.0 KB]

Our e-learning module How to read the Fast Break table explains it.

Four coupled global circulation model forecasts

Four coupled global circulation model forecasts

Three ensembles and a statistical model forecast

Image references

Original images used in this document are sourced from the Bureau of Meteorology under a Creative Commons 3.0 licence and from the NOAA which has a public domain policy. Annotations highlighting areas of interest have been added by Dale Grey.