Australian Weather

16 Sep 2025, 4:33AM UTC

Three separate earthquakes were detected across NSW on Monday night into Tuesday morning, with reports of shaking coming in from the coast to the state’s far west. According to Geoscience Australia, the trio of earthquakes occurred between 11pm on Monday and 8am on Tuesday AEST. Earthquake 1 The first tremor of this sequence was a 3.8 magnitude earthquake that occurred shortly after 11pm to the west of the Macquarie Marshes, roughly 50 km to the southwest of Carinda. Despite occurring in a sparsely populated part of the state, shaking from the earthquake was felt in at least three separate locations to the west of the epicentre. Earthquake 2 Monday night’s earthquake was followed by a shallow 3.7 magnitude earthquake near Muswellbrook in the Hunter Valley just after 2:20am on Tuesday. The epicentre of this earthquake was at the site of the Mount Arthur Coal Mine, a region that has seen a flurry of earthquakes in recent years, including magnitude 4.7 and 4.4 earthquakes on two consecutive days in August 2024. While mining operations can induce weak and shallow earthquakes, less than magnitude 2, research has shown that even large open pit mines are not able to trigger moderate or strong earthquakes. Earthquake 3 A third earthquake occurred near Bulahdelah just before 7:50am on Tuesday. This 3.1 magnitude tremor occurred at a depth of 9 km and was felt from Nelson Bay up to Forster and inland to Maitland, with Geoscience collecting around 100 felt reports across the Hunter and lower Mid North Coast regions. Image: Felt grid for the Bulahdelah earthquake on Tuesday morning. Source: Geoscience Australia. How common are earthquakes in Australia? Australia is in a relatively stable region of the planet for earthquake activity. Earthquakes are more common and stronger along Earth’s tectonic plate boundaries, which are the areas where large pieces of Earth’s crust meet each other. Australia is classified as a ‘stable continental region’, which means it sits far away from any major plate boundaries. While this does not make Australia immune to tremors, it means that most earthquakes in Australia are shallow, but they can still be powerful. On average, Australia experiences about 100 earthquakes of magnitude 3 or more each year, while earthquakes exceeding magnitude 5 only happen about once every two years. Stronger earthquakes exceeding magnitude 6 only happen about once per decade in Australia. One aspect of earthquakes that is often misunderstood is how much more powerful they become as you move up through the moment magnitude scale. Every whole unit you go up represents a 30-fold increase in the amount of energy released by the earthquake. This means that a magnitude 6 earthquake releases 27,000 times more energy than a magnitude 3 earthquake (30 x 30 x 30). You can track the latest earthquake activity in Australia on the Geoscience Australia website.

16 Sep 2025, 1:53AM UTC

Melbourne locals hoping for the first decent soaking of the 2025 spring would have been disappointed after rain dodged most suburbs overnight, with no rain recorded at the city’s main Olympic Park gauge – or in most other locations across the city – in the 24 hours to 9am Tuesday. Melbourne has received just 5.4mm of rainfall in the first half of September, with no more than 1.2mm on any day. The long-term monthly average for September is 58mm. The prospects for rain looked promising overnight as bands of moisture could be seen streaming across Victoria on the radar – so how did Melbourne dodge the rain? Image: Combined radar and satellite loop in the 12 hours from 8:30pm to 8:30am this Tuesday, September 16, 2025. The answer lies in Melbourne's 'rain shield' against moisture from the northwest. 'Rain shield' is not an official meteorological term. It’s a phrase we’ve coined to help you visualise the blocking effect of the Macedon Ranges, about an hour’s drive north of the Melbourne CBD, which act as a barrier to rain reaching the city when it comes from the northwest. Melbourne’s most reliable rainfall comes from the southwest, when showers stream across Port Phillip Bay and douse the city. Often this rain comes with cold fronts with their chilly, blustery winds – and as any Melburnian knows, these weather systems can strike even in midsummer. Two of Melbourne’s four heaviest rain days of 2025 to date came from southwesterly systems. On January 6, a bitterly cold system for that time of year delivered 24.6mm (and a maximum of just 18.9°C). On March 16, 18mm was recorded in another cold southwesterly, with an unseasonable maximum of just 19.1°C on the 17th. But not all significant Melbourne rain events originate in the southwest. Melbourne’s heaviest rain day for 2025 to date was January 12, when 31mm fell. That was a day of severe thunderstorms across a wide area – and winds in Melbourne that day blew from just about every direction (except the northwest). And of course, there are exceptions to every rule. Melbourne’s heaviest day of rainfall in the 2025 winter was June 8, when 15.2mm was recorded under consistent northwesterly winds. What happened to the 'rain shield' that day? A strong low pressure system centred over Victoria pulled moisture from the Southern Ocean up into central Victoria, then slung it back towards Melbourne as air rotated clockwise around the low. So that June 8 system wasn’t your typical northwesterly stream where air flows towards the southeast from the interior of the continent. That more typical pattern is illustrated well on today’s synoptic chart. Image: Synoptic chart for Tuesday, September 16, 2025. In summary, significant rain can and does occasionally fall in Melbourne when it comes from the northwest. But on days like today and yesterday with a broad-scale northwesterly stream across southeastern Australia, it’s less likely due to the blocking effect of the Macedon Ranges – which are only about half as high as the Victorian Alps to Melbourne’s northeast, but still hefty enough to influence Melbourne’s weather. Meanwhile the chance of showers persists in Melbourne this Tuesday and Wednesday, with a higher chance of the first meaningful spring rain from Friday through to Monday, as winds shift to the west and southwest. Our Melbourne forecast is here.