According to a weekly update from Solcast, a DNV company, Australia's entry into spring was marked by a pronounced divergence in weather patterns between the eastern and western regions. While temperatures remained above average across most of the country, solar irradiance and precipitation levels varied significantly depending on location.
Eastern Australia experienced generally favorable conditions for solar generation, with September irradiance averaging 5% above normal. Coastal areas, which host many distributed photovoltaic markets, stayed close to average levels, whereas inland regions supporting utility-scale projects saw increases of approximately 10%. Tasmania recorded particularly strong performance, with some areas reaching near-record or record irradiance levels for the Solcast data period, averaging 10% above normal. These high solar readings coincided with exceptionally dry weather across the southeast, where rainfall deficits exceeded 30 mm in much of New South Wales, Victoria, and Tasmania, continuing a trend of below-average precipitation observed throughout winter.
In contrast, Western Australia faced widespread irradiance deficits, averaging 11% below normal for September. The Pilbara region recorded levels around 10% below average, while the Goldfields-Esperance area saw larger drops ranging from 15% to 20%. Further inland, parts of the Gibson Desert experienced irradiance as much as 29% below average. These conditions were driven by several slow-moving low-pressure systems that brought persistent cloud cover and increased rainfall to inland areas. Notably, between September 5 and 9, large sections of Goldfields-Esperance received over 50 mm of rain, significantly exceeding the typical monthly total of just 10 mm.
Despite the reduced solar irradiance and higher rainfall in the west, temperatures across much of Western Australia remained above average, with parts of the Pilbara exceeding normal levels by more than 3°C. Meanwhile, the southeast experienced a combination of above-average irradiance, unusually dry conditions, and temperatures generally 1–3°C higher than normal.
Solcast generates these figures by tracking clouds and aerosols at a 1-2km resolution globally using satellite data and proprietary AI/ML algorithms. This approach enables high-resolution irradiance calculations with a typical bias of less than 2% and supports cloud-tracking forecasts. The data is currently utilized by over 350 companies managing more than 350 GW of solar assets worldwide.
Sources: pv magazine.