The week of 24–31 May 2026 delivered a textbook late-autumn market across both the NEM and WEM — opening with moderate winter pricing, escalating sharply mid-week on cold-driven demand, then collapsing on Friday as mild conditions and strong renewable output flooded supply. NEM-wide spot averages peaked on Tuesday 27 May, with NSW1 reaching a daily average of $157/MWh and SA1 hitting $164/MWh, before a dramatic reversal on Friday 30 May saw VIC1 average just $20/MWh and SA1 average an unusually low $24/MWh. The mid-week surge reflected a combination of elevated heating demand, tight gas-fired dispatch, and constrained interconnector flows — particularly on the Tasmanian corridor.
Tasmania was the week's most constrained region from a network perspective, with the T_BLINK_TV_NGZ constraint binding persistently from 25 May through to 31 May, recording shadow prices of $7.308 million on multiple occasions. Despite this, TAS1 spot prices remained comparatively stable in the $87–$110/MWh range across the week, with the constraint primarily acting to limit interconnector flows rather than drive local price spikes. Tasmania also achieved 100% renewable penetration on multiple evenings, underpinned by hydro and wind generation.
In Western Australia, the WEM ran consistently above NEM equivalent averages for much of the week, with WA1 daily averages ranging from $97/MWh to $166/MWh and three notable intra-day price spikes recorded across Wednesday through Friday. The broader market narrative heading into June is one of seasonal transition — winter demand is arriving, but renewable output remains capable of suppressing prices sharply during off-peak periods, creating a volatile intra-day spread that energy managers and contract buyers will need to navigate carefully.
The week's pricing trajectory was distinctly two-phased. The first half (24–27 May) saw demand-driven escalation across all NEM regions, with NSW1 averaging $157/MWh on 27 May (intraday high of $247/MWh), SA1 averaging $164/MWh (high of $250/MWh), and QLD1 averaging $141/MWh (high of $232/MWh). VIC1 also climbed to a $127/MWh average on the 27th. TAS1 remained the relative outlier, with averages more contained in the $101–$110/MWh band through the mid-week period, though it did record an intraday high of $449/MWh on 26 May — likely associated with a constraint activation coinciding with a brief supply-demand imbalance.
The second half of the week saw a pronounced price collapse. By Friday 30 May, VIC1 averaged $20/MWh (minimum of near-zero), SA1 averaged just $24/MWh, and NSW1 averaged $41/MWh. QLD1 averaged $55/MWh. Minor negative pricing events were recorded across QLD1, NSW1, SA1, and VIC1 during overnight and early-morning intervals on both 30 and 31 May, driven by oversupply as renewable generation outpaced demand during low-load windows. These were brief and shallow — the deepest sustained negative print was QLD1 at approximately -$7.33/MWh on 28 May, with most other negative intervals sitting in the -$0.10 to -$2/MWh range.
The WEM had an active week. WA1 daily averages tracked broadly above $100/MWh for most of the period, peaking at $166/MWh on Friday 29 May — notably elevated relative to the NEM's concurrent price collapse. Three significant intraday price spikes were recorded: $254.94/MWh on 28 May at 10:50, $310.03/MWh on 29 May at 04:55, and a week-high of $367.44/MWh on 30 May at 06:10. Each spike was isolated to a single trading interval and resolved quickly, suggesting short, sharp supply shortfalls rather than sustained tightness. The WA1 daily minimum remained elevated throughout — never dropping below $38/MWh on any given day — reflecting the WEM's structurally different supply-demand dynamics compared to NEM regions experiencing overnight oversupply.
Tasmania delivered 100% renewable penetration on at least six separate evening windows across the week, from 25 May through to 31 May. These events were predominantly hydro-led, with hydro output ranging from approximately 850 MW to over 3,300 MW depending on the interval, complemented by wind generation of between 150 MW and 519 MW. Prices during these windows generally held in the $80–$106/MWh range, indicating the market remained balanced without significant oversupply pressure in TAS
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