WA1 experienced a moderate price spike to $253.22/MWh in the 04:55 interval on 20 June 2026, representing a $6 increase from the previous interval. Prices had been escalating over the preceding ten minutes, rising from $151–154/MWh at 04:30–04:35 to $237–246/MWh by 04:50 before the final spike.
The binding constraint F_MAIN+RREG_0220 was active throughout the spike period with marginal values ranging from $4.98 to $15.49/MWh, indicating supply-side constraints limiting available generation capacity. The constraint's contribution to the spike accounts for approximately 5–15/MWh of the price elevation, with the remainder driven by tightening system conditions as demand rose against a constrained generation envelope dominated by coal (1119 MW), gas (631 MW combined), and wind (1118 MW total).
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.