The WEM in Western Australia experienced a significant price spike to $346.97/MWh during the 20:45 trading interval on 3 June 2026, representing a 134% increase from the previous interval's $148.64/MWh. Prices continued escalating sharply to $370.42/MWh by 20:55, indicating sustained market tightness across multiple consecutive intervals.
The primary driver appears to be binding transmission constraints, particularly the F_S++HYSE_R60 constraint which showed elevated marginal values ($25/MWh) immediately preceding the spike, indicating congestion on critical network paths limiting available generation capacity. The rapid price escalation during evening peak demand (20:45 timeframe) combined with the generation mix showing moderate wind output (542 MW combined) and reliance on gas generation (1,292 MW across OCGT and CCGT units) suggests demand exceeded readily available affordable supply, forcing the dispatch of marginal peaking plant or invoking scarcity pricing as the constraint binding intensified the effective supply shortage.
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.