Anecdotally, the summer that just wrapped up felt relatively quiet on the price front — with more subdued conditions than we’d usually have come to expect. 

To see whether the data backs this up, this short article looks at intraday 2-hour price spreads to assess whether this past summer saw less volatility than in recent years. Before looking at these spreads, we’ll firstly touch on the underlying market conditions and drivers that may help explain what we find.

Market conditions and underlying drivers

In this article we won’t cover drivers for these price outcomes in depth, but it is worth highlighting some of the underlying conditions for summer 2025-26 (and how they compare to conditions in other recent summers).

Note this is not an exhaustive list, and other factors will have certainly played a part… however at a high level:

• Wind production was notably higher than prior summers. This partly reflects the increased production of several new large wind farms, including Golden Plains in Victoria and the MacIntyre and Clarke Creek wind farms in Queensland.
• Temperatures were above average across most major population centres, but milder than the record heat of recent summers. The BOM reported this week that temperatures throughout summer were above average in most capital cities, but a step down from the record-breaking heat of 2024-25, which was the second-warmest summer on record nationally. Adelaide was a notable exception, recording its fourth-warmest summer on record.
• Coal availability was broadly similar to last summer, with no sharp decline amongst the NSW or QLD coal fleet — though a gradual 3+ year downward longer trend in coal availability can be observed in VIC and NSW.
• Installed utility-scale battery storage across the NEM has grown significantly, with installed BESS capacity rising sharply over the past 12 months — a trend we covered in last week’s wrap-up.
• Behind-the-meter storage continues to grow. The is an area of increasing interest for us in terms of understanding wholesale price dynamics. As noted last week, current reporting indicates at least 4.7 GWh of home storage has been installed since the start of this financial year.

2hr price spreads over the past four summers 

Here we’ll look at price spreads over a 2 hour duration. This is one of the most common measures of intra-day volatility, but price spreads across the other common measured durations (e.g. 1hr, 4hr, etc.) show a similar general trend across this summer.

Each of the charts shown below plots each intraday (calendar day) 2hr spread i.e. the difference between the average of the highest priced 24 dispatch intervals and the average of the lowest priced 24 dispatch intervals each day. The line series in each chart shows the 7-day rolling average of the spread, and the horizonal reference line displays the average daily spread over each summer.

QLD

In terms of price spreads, this past summer was unusually quiet in Queensland, with a mean 2hr spread of $144/MWh — less than a quarter than the extremes of summer 2023-24, and less than half from the previous summer.

Source: NEMreview

NSW

In New South Wales, the average 2hr spread also decreased from levels experienced in the previous two summers, but not as low as Summer 2022-23 (which was one of the mildest summers across Australia in the past decade). The region saw a compressed average 2hr spread ($282/MWh) but saw six days where the spread was above $500, including material price volatility on January 10th.

Source: NEMreview

VIC

Spreads in Victoria also were materially flatter in summer 2025–26, with the region experiencing its lowest average spread across the past four summers — in the chart below we can see spreads were notably low and flat across February especially. 

Source: NEMreview

SA

The seasonal average of $582/MWh in SA looks like an outlier compared to the other four regions — but is highly influenced by just one day: 26th January, when the 2-hour spread reached $19,622/MWh.

On that evening temperatures in Adelaide reached 40°C, and the region’s battery fleet ran close to empty.  If we remove that single day, the SA summer average 2hr spread falls to around $316/MWh (i.e. below the average of each of the previous three summers) —  with December ($286/MWh) and February ($248/MWh) both below the equivalent months in 2024-25. 

Source: NEMreview

Tasmania

Summer is generally a mild season for prices in TAS. Despite this, price spreads also decreased this past summer — demonstrating the lowest average 2hr spread over the past four summers.

Source: NEMreview

Final remarks

The data suggests our anecdotal impression was broadly correct: by most measures, price volatility over summer 2025–26 was relatively subdued compared to recent history.

The more interesting question is whether this easing proves temporary — reflecting a favourable mix of seasonal conditions — whether volatility is increasingly being displaced into other seasons, or whether it points to a more structural shift as battery penetration rises, with broader implications for the business case for supply still lining up to enter the market.