The WEM in WA1 experienced a sharp price spike to $314.03/MWh in the 10:20 trading interval on 4 September 2026, more than doubling from the prior interval's $166.24/MWh. This represents a single-interval major price event in an otherwise moderately elevated pricing environment that had been gradually climbing from ~$146/MWh over the preceding 25 minutes.
The spike coincided with multiple binding constraints on the system, including F_TASCAP_RREG_0220 (marginal value $5.49) and F_T+RREG_0050 (marginal value $5.41), indicating active constraint-driven scarcity pricing. With total system generation of approximately 2,763 MW and a generation mix dependent on wind (592 MW combined), gas (834 MW), coal (591 MW), and battery (248 MW), the price acceleration suggests a rapid tightening of available dispatchable capacity during the interval, likely driven by reserve or network constraints rather than wholesale shortage, as the binding constraints account for only ~$10.90/MWh of the $147.79/MWh intra-interval rise.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.