The WEM experienced a significant price spike in WA1 at 04:55 on 29 May 2026, with the spot price reaching $310.03/MWh—a 42% increase from $218.76/MWh just five minutes earlier. This spike occurred as an isolated event within a single trading interval during the early morning period.
The rapid price escalation appears driven by binding transmission constraints, particularly the F_MAIN+RREG_0220 constraint which showed marginal values up to $18.39/MWh and dominated the constraint set during this period. The timing during off-peak hours (04:55 AM) combined with elevated OCGT generation (~712 MW) and reliance on dispatchable thermal and battery resources suggests the constraint restricted available supply, forcing the market to marginal generation costs significantly above recent levels as demand-side pressure or network limitations reduced viable generation pathways.
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.