Guide
How PetrolCast forecasts
petrol prices
Three signals. One clear recommendation. Here's how it works.
Three signals, combined
1. The local price cycle
Every Australian capital city has a characteristic price cycle — a recurring boom-bust pattern driven by retail competition. Sydney and Melbourne run on roughly 6-8 week cycles. Brisbane's is tighter at 2-4 weeks. Perth and Adelaide have less pronounced but still visible cycles. PetrolCast tracks daily average prices going back 90 days per city to identify where in the cycle you currently are: rising, at peak, falling, or approaching trough.
2. Global oil market direction
We fetch the daily Brent crude spot price and the Singapore MOGAS 95 price — the direct benchmark for Australian imported fuel. When either of these has moved materially over the past 14 days, that signal is incorporated into the forecast. A sustained rise in Brent typically translates to higher retail prices in Australia within 2-3 weeks. A sustained fall can push the cycle trough lower than historical averages.
3. The AUD/USD exchange rate
Australia imports refined fuel priced in US dollars. A weakening Australian dollar raises the AUD cost of every barrel even if USD prices haven't moved. We track the 14-day trend in AUD/USD alongside the oil price trend. If the AUD has weakened and oil prices have risen simultaneously, the forecast factors in a larger-than-usual price increase at the pump.
How the signals combine
The three signals are combined to produce a scenario classification. There are six possible scenarios:
Higher
Oil prices and/or a weak AUD are pushing import costs up materially. Prices at the pump are likely to be higher over the next 4 weeks than the recent average.
Relief
Oil prices have fallen and/or the AUD has strengthened. Import costs are lower and the next cycle trough may be meaningfully cheaper than recent troughs.
Stable
Market signals are flat. The cycle will continue its normal rhythm without unusual macro influence.
Mixed
Oil prices and the AUD are moving in offsetting directions. The net import cost change is small, but uncertainty is elevated.
Margin squeeze
Import costs have risen sharply but retail prices haven't yet adjusted fully. Retailers are running compressed margins. A price rise is likely soon.
Margin bloat
Import costs have fallen but retail prices remain elevated. Retailers are earning above-average margins. Competitive pressure may push prices down faster than the cycle alone would suggest.
What PetrolCast doesn't claim
Petrol price forecasting is genuinely hard. Retail prices are influenced by dozens of factors including individual retailer strategy, local competition, unexpected global events, and government policy changes. PetrolCast provides directional guidance based on the signals available — not a precise price prediction. Every recommendation includes a confidence level, and when markets are volatile we'll tell you that uncertainty is high rather than projecting false precision. The goal is to give you an information edge, not a guarantee.