The Summer Reliability Assessment (SRA) covers the upcoming summer season, providing an evaluation of reliability for projected risk periods while identifying potential reliability issues of interest and regional topics of concern. Among the findings:
- Continent-wide, the 2026 summer risk profile is characterized by rising demand, significant resource additions in many areas, the prospect of challenging hydrological conditions, and unpredictability associated with large loads.
- All areas have adequate anticipated resources for normal summer peak load conditions, according to the assessment; however, three areas face elevated risk of supply shortfalls during periods of more extreme summer conditions, including the Western Interconnection’s Northwest subregion.
- An influx of resources, primarily solar and battery but also natural gas-fired generation, has outpaced demand and boosted reserves, easing resource adequacy concerns across the continent.
- Large loads pose operational challenges for the summer. Recent events in which large loads unexpectedly disconnected from the grid in the Eastern Interconnection and ERCOT highlight the need for operational readiness this summer and illustrate why NERC is closely examining the potential risks posed by large loads.
- The overlap of early summer heat and spring maintenance outages can lead to reliability risks.
NERC Summer Reliability Assessment: Western Overview
Each year, WECC partners with the North American Electric Reliability Corporation (NERC) and the rest of the Electric Reliability Organization (ERO) Enterprise to develop the NERC SRA. This assessment evaluates system resource adequacy and reliability across North America for the upcoming summer season. Below are highlights from the assessment specific to the Western Interconnection.
- Common reliability concerns across the Western Interconnection for summer 2026 are threats from wildfire, resource adequacy in periods of extreme heat, and drought, which exacerbates the wildfire threat and can lead to diminished hydro output. These concerns vary in severity in each of the eight WECC subregions.
- Wide-area heat events or wildfires that affect resource and transmission availability across the Western Interconnection are a concern. The ability to import energy may be limited during these events.
- Supply chain constraints and economic uncertainty may affect planned resources across the interconnection.
- Along with challenging hydro conditions, the Northwest’s elevated designation centers on a nearly 5% increase in demand projected for this summer from the 2025 SRA, a nearly 2% decrease in existing resources, and a significant drop in planned resources.
Subregion Reliability Highlights
British Columbia: Peak demand is projected to increase 2.4% over last summer’s forecasts, while anticipated resources increase by almost 16%. In WECC's analysis, no loss of load emerged in a range of conditions.
Alberta: Peak demand is projected to increase 2.1% over last year’s forecasts, while anticipated reserve margins exceed the prescribed margin level. In WECC's analysis, no loss of load emerged in a range of conditions.
Northwest: Peak demand is projected to grow 4.6% over last summer’s forecasts, while anticipated resources show a 1.5% increase in energy availability, leading to tighter margins. Supply chain constraints and economic uncertainty may affect planned resource additions. The elevated risk of shortfalls in the assessment occurs in August and September.
California: Extreme heat and wildfires may affect generation and transmission resources and remain a reliability concern. Variability of inverter-based resources is a concern, particularly in the evening when solar generation wanes and wind generation can be curtailed due to Santa Ana Winds.
Mexico: The subregion added 1 GW of gas-fired generation since last summer, significantly improving the outlook from the 2025 SRA. Operating reserves are a concern during periods of extreme heat and elevated demand, however. Anticipated reserves are projected to be 16% higher, but some generating units have reached advanced operational age, resulting in an increase in the forced outage rate. This raises the risk of capacity shortfalls, potentially compromising system reliability during peak summer demand.
Basin: Peak demand is projected to increase by 4%, due in part to a significant decrease in demand response availability, while anticipated resource capacity is expected to increase by 16% from last summer’s forecasts.
Rocky Mountain: Peak demand is projected to decline by 3%, while anticipated resource capacity is expected to increase by 15%. Climate change and ecological factors are raising the wildfire risk in the subregion, although the entities have engaged in substantial mitigation efforts.
Southwest: Peak demand is projected to increase by 10% over last summer’s forecasts, while anticipated resource capacity is expected to increase by 33% since last summer’s forecasts. The subregion faces grid reliability concerns posed by large loads if new generation resources are delayed as new load comes online.
Summer Conditions and Drought Affecting the Bulk Power System
Forecasts indicate above-normal temperatures for much of the West this summer as an El Nino weather pattern is expected. Drier-than-normal conditions are expected in the Northwest, where the snowpack is below average. In Canada, higher-than-normal temperatures are expected in the northeast. Snowpack in Canada is generally in average condition, with a pocket of below-average snowpack in southwest British Columbia. To learn more about the expected summer weather and operating conditions, view the Reliability in the West Discussion Series: Assessing Summer Conditions and Readiness.
Extreme Heat
The summer peak declined in the Western Interconnection in 2025, to 163 GW from 168 GW in 2024, as most of the West saw a moderation in heat compared to 2024. And, while the interconnection experienced relatively few emergency events, there were heat events that stressed the system.
- A heat wave in western Canada from late August through early September broke records in British Columbia and exacerbated drought conditions. Parts of western Canada saw generation outages that triggered energy emergency alerts (EEA).
- In Mexico, generation losses in late August triggered EEAs.
- In the Rocky Mountain subregion, Utah and Nevada recorded their warmest years on record.
Challenging Hydro Conditions
Drought conditions are either in place or are likely to develop this summer throughout much of the interconnection. This could affect hydropower generation (hydro has the second-most nameplate capacity installed in the Western Interconnection).
In the Northwest subregion, where hydro makes up more than half of the resource mix, the snow water equivalent was at 52% of normal as of April 1. While the water year is forecast to be about average in the Columbia River Basin, snowpack melted earlier in the year. This has implications for the expected resources available in the Northwest.
The Southwest subregion is less reliant on hydro, but one significant hydro facility on the Colorado River System, the 1 GW Glen Canyon Dam at Lake Powell, had been projected to be unable to generate power due to low water levels as soon as August 2026. The Bureau of Reclamation has taken steps to prevent this, announcing plans in late April to release enough water from the Flaming Gorge Reservoir to increase Lake Powell's elevation to sufficient levels for power generation.
Downriver, Hoover Dam is operating in shortage conditions, but the most recent projections indicate Lake Mead will maintain levels needed to generate power at the 2 GW facility throughout the 24-month period studied.
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