Jane's Weekly Update: 26th September 2025

Over the next week most of the action will be in the southeast.

If you're concerned about what that means for the AFL Grand Final, do rest assured that the timing is great - we are in a break. Grand Final Saturday is likely to feature lots of sunshine with a mild top of 19C or 20C. That's after the potential for a dramatic change on Friday afternoon (showers and the risk of storms), but that clears out quickly.

A series of cold fronts is crossing the southeast, and that'll feature two 'cut-off' lows early and mid to late in the week, to enhance the activity even further.

First of all - there is no proper connection to tropical moisture, so the rain doesn't extend very far inland. But if you're in Tasmania or much of southern VIC (not central and east Gippsland), or southeastern SA, then it's a good 25 to 50 mm of rain (more in Tasmania).

A big weather system heads for Queensland but barely brushes the coast - that rain is going to stay well offshore.

The southwest is blocked by high pressure so they are only brushed by the southeast systems on their way past.

The latest modelling for the Pacific Ocean Index has arrived, and a few more models have headed near/across the threshold for La Nina, while the rest are on the La Nina side of Neutral or purely Neutral.

It is important to note that the Australian threshold is more negative than the American threshold, so you will hear the Americans talk about La Nina a lot more than BoM does.

BoM has now finally declared the Negative Indian Ocean Dipole that we have been in since late July (they wait until we've been in it for 8 weeks before letting you know that it occured). That will slowly Neutralise as we head through the rest of Spring, as the monsoon takes over.

The potential La Nina would mean that the Pacific as a whole encourages additional moisture to be pushed towards Australia. We already have warmer than average waters around the top half of the continent, and incredibly warmer than average water in the Tasman Sea - so we already have an enhanced source of moisture and the potential La Nina just increases that further.

But as always, that is just one part of the rainfall equation. It will lead to above average rainfall - but only for those in the path of low pressure, as you need both moisture and instability to work together to bring rain. We know about the moisture for the months ahead, but not where the lows are likely to be.

For all of this and more, and if you have 9 minutes to spare, don't miss my video update:

In this series I'll take you through the drivers of our weather, highlighting any changes over time and things to watch out for (generally every Friday). It covers weather elements like temperature and rainfall, and how they are driven by moisture from the Pacific and Indian Oceans, as well as bursts of energy from low pressure (SAM and MJO).

See and hear my commentary as I take you through the weather pattern's effects on our rain and temperatures in detail over the next week, with a brief look at week 2 and beyond as well.

Plus what is driving our weather in the weeks and months ahead, with the latest on El Nino/La Nina, the Indian Ocean Dipole (IOD), the Southern Annular Mode (SAM controls our weather systems), and the Madden Julian Oscillation (MJO connects tropical moisture to our weather systems).

I update this commentary each week, generally on Friday's. Make sure you are signed up (free or a subscription) so you don't miss an update.

Stay up to date with the forecast specifically for your area in our hour by hour outlook for the next 10 days. Download our app for iPhone and Android.

As always, you can see each of these graphics as soon as they update, as well as more information about them under our Rain Outlook and Seasonal Outlook pages within Jane's Update, along with our Snow Forecast in the snow season.