Ex-TC Koji funnels much-needed moisture to NSW and Victoria

Parts of New South Wales that have barely seen a drop of rain in the first half of January 2026 will see showers and storms this Wednesday as a trough crosses the state.

Showers and storms could also develop in northeastern Victoria, although Thursday looks more likely for any meaningful rain south of the Murray.

Any rain that falls in central parts of New South Wales this Wednesday and Thursday will be especially welcome.

Predicted rainfall accumulations for NSW and adjacent areas up until Tuesday, January 202, 26
Image: Australian rainfall deficiencies for the last three months of 2025. Significant rain has continued to be absent from most of the rainfall-deficient areas in NSW (red shading) over the first two weeks of 2026, which is why any rain this week will be welcomed by most locals. Source: BoM.

Examples of large population centres in need of rain

The city of Dubbo (which lies close to the geographical heart of NSW in the Central West Slopes and Plains forecast district) saw less than a third of its average monthly rainfall in each of the last three months of 2025.

January has also been relatively dry to date in Dubbo, with just 10.4mm of rain as we approach the halfway mark of the month (January average 55.7mm).

It has been a similar story in the NSW Southern Tablelands forecast district and the ACT (which lies within that region).

Canberra closed out 2025 with three months that saw roughly half their average rainfall, while only 8.6mm has fallen to date in January 2026 (monthly average 56.8mm).

Ex-TC Koji now influencing weather in southern Australia

"The broad low pressure trough is extending from ex-TC Koji in the north all the way down to central Victoria," Weatherzone meteorologist Joel Pippard explains,

"The trough will meet up with an upper trough and cold pool from today. As the system tracks west, bringing scattered to widespread thunderstorms on Thursday, it will spawn a coastal trough off the NSW coast.

"The moisture feed from the tropics and the Tasman Sea will deliver heavy rainfall along the NSW coast, heaviest in the far south, with a growing powerful swell to impact the coast from Friday to next Tuesday."

NSW South Coast deluge appears likely later this week

Image: Predicted rainfall totals for the South Coast of NSW and adjacent areas up until Tuesday, January 20, according to the ECMWF model.

As a low pressure system develops just off the NSW South Coast on Friday, heavy rain will fall in that region and nearby areas.

The South Coast is another part of NSW that been very dry lately.

Everyone knows Bega because of cheese (it’s not shown on the map above but is located just north of Merimbula). Cheese means dairy country, which usually means relatively high rainfall if an area is not widely irrigated – and this area isn’t.

But Bega finished off 2025 with four months of significantly below-average rainfall and hadn’t received a drop of rain in the first two weeks of 2026 to 9am this Wednesday.

By next Tuesday, Bega could have received totals in the vicinity of 200mm of rainfall. We’ll keep you posted on the NSW South Coast low later this week as it develops.