In Australia's five largest capital cities, retail petrol prices move in cycles — not because wholesale costs changed overnight, but because retailers coordinate pricing phases. The ACCC is clear: these cycles are the result of retailer pricing policies, not sudden changes in the cost of fuel at the terminal.

The typical pattern:

1. Prices fall gradually over one to three weeks

2. They spike sharply over 24–48 hours

3. The cycle repeats

Melbourne's recent cycles have lasted between 33 and 41 days end to end, with the sharp rise phase often taking just 13–19 days from trough to peak. That is why an overnight jump feels so dramatic — it is built into how the market works.

Sometimes the overnight move is not the cycle — it is a wholesale price increase flowing through. Terminal gate prices adjust when international benchmarks shift. If a refinery outage, OPEC decision, or currency swing hits mid-week, you may see pump prices rise within days.

The ACCC estimates international benchmark changes can take around two weeks to fully pass through to retail, but competitive pressure and cycle timing can accelerate that.

Government decisions can cause instant, uniform increases. When temporary excise relief ends or tax rates are indexed, every station moves on the same day. That kind of jump is policy-driven, not market-driven — and it affects petrol and diesel equally.

| Signal | Likely cause |

| --- | --- |

| Prices up 8–15 cpl at most stations on the same day | Price cycle entering peak phase |

| Gradual rise over a week across all fuel types | Wholesale / international benchmark movement |

| Identical increase at every retailer nationwide | Tax or excise change |

| Diesel up, unleaded stable | Global gasoil supply issue |

An overnight fuel jump in Melbourne is usually the peak phase of the retail cycle, sometimes amplified by rising wholesale costs. It is frustrating — but predictable. Track cycle position and compare live prices before the spike hits.

Tools: station directory · live map · Fuel price cycles