Day-Ahead and Real-Time Price Trends by Components and by Zone
In June, Ontario’s wholesale market experienced higher prices across all zones in real-time compared to day-ahead – with the exception of the Northwest zone. The Northern zones continued to show low prices in June largely as a result of congestion, while the Ottawa zone saw higher prices. DA zonal prices ranged from $30/MWh (Northwest) to $48/MWh (Ottawa), while Real-Time (RT) zonal prices ranged between $24/MWh (Northwest) to $54/MWh (Ottawa).
The DA and RT price by zone and by component for the past month is shown below. Prices in the Northwest zone and Ottawa zone were mainly impacted by congestion due to reduced capacity on major transmission interfaces and several hours of high exports to Quebec.
Day-Ahead and Real-Time Prices
June experienced a higher monthly average price with less frequent price spikes above $200/MWh compared to May. There were 13 real-time hourly OZP spikes greater than $200/MWh. The average hourly day-ahead OZP was $44.93/MWh in June, while the real-time OZP was $48.68/MWh. The highest real-time OZP was $657.94/MWh (on June 30, HE 20). The peak Ontario demand in May was 23,526 MW (on June 30, HE 19). The June Ontario peak demand was 2,696 MW higher than the peak in May – driven by increased temperatures. The Ontario demand on June 30, HE 20 – when OZP hit its highest level – was 23,361 MW, which is still below the peak demand of more than 24,000 MW in the summer of 2025.
OR Prices
There were less real-time Operating Reserve (OR) price spikes in June compared to May. Much lower day-ahead and real-time average monthly OR prices were observed in June, in contrast to May as well as June 2025. The average monthly day-ahead 10S price was $9.03/MW, while it was $6.19/MW in real-time. The highest real-time OR price spike was $555.94/MW and occurred at the same hour as the highest real-time OZP spike. In the day-ahead market, the most common 10S price was $0.10/MWh (occurred 37% of the time). This was also the most common price in the real-time market (occurred 15% of the time). The very low OR prices last month compared to May are likely due to the increased generation from energy storage resources observed last month. In June, there was about 79 GWh in energy storage output while in May, there was about 47 GWh – marking the highest monthly total storage output since the launch of the renewed market. In June, two new storage units came online. Overall, the IESO will be adding up to 3,000 MW of 4-hour storage by 2029, which is expected to put downward pressure on OR prices.
The highest day-ahead OR price was $184.34/MW, which occurred on June 30, HE 19. The day-ahead energy price was $231.71/MW at this time. The day-ahead OR price exceeded the day-ahead energy price in 15 hours or 2% of total hours in June. This trend is significantly lower than the amount in May, where 276 hours (37% of total hours) had the OR price higher than the energy price – meaning that in these hours the OR market was tight and reserve prices put upward pressure on energy prices due to co-optimization. OR prices can put upward pressure on energy prices during the freshet period between April and May, as many hydroelectric units are operating on a must-run basis and cannot provide OR.
Real-time OR prices were low (i.e., near $0.10/MW) for many hours. There were some hours with real-time OR price spikes, coincident with real time OZP spikes. The highest real-time OR price was $555.94/MW on June 30, HE 20. In contrast to May, the real-time OR prices exceeded the real-time energy prices across 5 hours or 1% of total hours in June. This is higher compared to May where 82 hours or 11% of total hours OR prices exceeded the energy prices.
Zonal Prices and Congestion
The average real-time nodal price (LMP) across Ontario for June is shown in the figure below. In contrast to May, all nodes across Ontario are mainly elevated in price. The nodes in the northern zone tended to be slightly lower than all other zones while the rest of the Ontario nodes were higher. There continues to be a structural divergence in prices between southern and northern Ontario.
In June, compared to May, there were less nodes in the Northern zones with a low LMP of close to - $100/MWh. The minimum LMP was closer to the range down to -$40/MWh.
In June, there was moderate congestion across a few zones in the day-ahead market. The Northwest zone saw the most hours of congestion with a low of - $157.07/MWh. The Northeast zone also observed mainly negative congestion with a low of - $71.35/MWh. Congestion in the East and Ottawa zones occurred mostly at the same hours at the beginning of the month. The East and Ottawa zone saw a high of $26.32/MWh and high of $41.03/MWh respectively. The West zone saw minor hours of congestion with a low of -$28.88/MWh. Note that negative congestion typically means there was a constraint exporting energy from a particular zone (and lower energy prices), while positive congestion is the opposite.
In real-time, the Northeast and Northwest zone saw several hours of consecutive negative congestion throughout the month. The Northwest zone saw mainly negative congestion with a low of - $522.70/MWh (on June 30, HE 20). The Northeast zone saw a high of $42.32/MWh (on June 26, HE 21) and a low of - $204.12/MWh (on June 11, HE 20). The lowest congestion observed in the Northwest zone in June was at the same hour as the highest RT OZP observed.
In most of June, there were several outages on the East-West Transfer East (EWTE)/East-West Transfer West (EWTW) and Flow Into Ottawa (FIO) interfaces. There also continued to be reduced capacity on Flow-South (FS) (FS is operating at minimum capacity) for June. The outages on the northern interfaces as well as FIO impacted the congestion observed in the Northern zones and Ottawa zone respectively.
Other than the Northern zones, in real time, there was high congestion in the Ottawa zone at the same time as the East zone. The Ottawa zone observed only a few spikes above $100/MWh. The high in the Ottawa zone was $531.94/MWh and the high in the East zone was $161.04/MWh. Most congestion was concentrated at the beginning of June. The Essa zone had minor congestion except for one hour with a low of -$99.27/MWh. The Southwest zone had minor congestion with a high of $11.07/MWh and a low of -$24.42/MWh.
In June of this year, the Northern zones saw a high number of congested hours, similar to May 2026 and June 2025. The number of congested hours in the Southwest zone has dropped in June, compared to May. Congestion has also appeared in the Niagara zone but was minor. The southwest zone continues to experience many hours of congestion.
As shown in the figure below, June experienced major northern interfaces with reduced capacity, specifically the EWTE/EWTW and FS, similar to what occurred in May. In June, there was also reduced capacity on the MISSE/MISSW interfaces. The FIO had much more frequent occurrences of reduced capacity in June, in contrast to May.
