WEM prices in WA1 spiked sharply to an average of approximately $372/MWh across five consecutive 5-minute trading intervals from 01:10 to 01:40 on 15 June 2026, representing a sustained elevation of roughly 50% above preceding price levels around $241/MWh. The spike occurred during overnight trading hours with a diverse generation mix comprising coal, gas (OCGT and CCGT), wind, battery storage and solar.
The price elevation was driven by binding constraints, particularly a constraint with marginal value of $10.99/MWh and another with marginal value of $3.73/MWh that remained consistently binding across multiple intervals. These constraint marginal values directly contributed to the elevated price floor during the spike window. The underlying tightness was supported by a generation dispatch pattern reliant on higher-cost gas and thermal sources, suggesting demand or supply conditions that necessitated constraint-limited dispatch rather than least-cost generation sequencing.
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.