Jane's Weekly Update: 23 May 2025

We currently have a big weather system crossing the southeast. This delivered huge rainfalls to eastern NSW, but it can't spread far west thanks to blocking high pressure. We're in the last part, and the rain clears away early tomorrow.

A cold front crosses the Bight, after bringing a chill and showers to the southwest - but it won't pass through the southeast, fizzing out as it arrives on Saturday into Sunday.

The next cold front has more luck, crossing the southeast on Monday into Tuesday. This brings wintry showers, gusty winds and alpine snow - and lets colder air work its way up the east coast. There isn't a connection to tropical moisture (again thanks to blocking high pressure) so the coast does well, the ranges do well (on the southern and western sides) and it fizzes out further inland. The left overs from this dominate the weather pattern for the rest of the week.

Meanwhile, there is a big surge of moisture coming in from the northwest. This is the start of one of those juicy, northwest cloudbands that if they connect to a system in the south, deliver good, soaking rain. You guessed it though - there is no connection thanks to blocking high pressure - so this rain falls over the interior, then the left overs cross Queensland late next week.

However, the next weather system arrives in the west late next week, another big push of moisture from the Indian Ocean. Will this be the one that makes it through to the southeast? Euro's week 2 modelling likes it so it is definitely one to watch.

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At a global and seasonal scale, the Pacific Ocean is in a neutral state and won't be a big factor in 2025's weather. We have warmer than average waters off eastern Australia that act as a great source of moisture when the weather pattern pushes them to us.

The Indian Ocean is much more interesting.

The models have been forecasting a negative phase for this winter and spring - and now we are seeing the first signs of the ocean starting to turn.

Look at the Indian Ocean box and see the first bits turning blue. That's the beginning of a transition to cooler than average water over there.

If the box continues to 'turn blue' then we end up with an imbalance, and the atmosphere takes note and tries to put it back in line.

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This is great for us, because the atmosphere actively encourages moisture to move eastwards across the Indian Ocean and into Australia.

The atmosphere actively encourages those juicy northwest cloudbands.

We are seeing the first inkling of this transition now... and the forecast over the next few months looks very promising for a full transition into negative (the green zone).

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Watch my full explanation in this weeks video:

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.