The WEM experienced a sharp price spike to $371.72/MWh in WA1 during the 20:40 settlement period on 21 June 2026, representing a 51% increase from the preceding five intervals which averaged $245.78/MWh. The spike occurred across a single trading interval with elevated levels of wind, gas-fired generation, and battery output already online.
Multiple binding constraints with positive marginal values indicate that network or system limitations were constraining available supply during this interval, with the highest-marginal constraint contributing approximately $12.24/MWh to the price floor. The sudden jump from baseline prices of ~$245/MWh to $372/MWh, combined with evidence of binding constraints across regulating service requirement equations, suggests that operational constraints on either network capacity or reserve procurement became binding, reducing effective available supply and forcing the market to activate higher-cost marginal generation to meet demand.
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.