MISO Reports 134.7 GW of Winter Capacity Offers Against a 113.4 GW Peak, With 3.6 GW Added and 2.3 GW Retired
- Analysis Capacity & Wholesale Markets Policy & Markets
Marin Holt
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- Winter capacity offers secured in the Planning Resource Auction: approximately 134.7 GW
- Projected winter peak demand: approximately 113.4 GW
- New capacity additions offered: approximately 3.6 GW, led by natural gas
- Suspensions and retirements: 2.3 GW of available capacity removed
MISO released its winter readiness assessment for the 2026-2027 season on October 28, 2026. The grid operator is based in Carmel, Indiana. Its annual Planning Resource Auction secured approximately 134.7 gigawatts (GW) of winter capacity offers. That exceeds the projected winter peak demand of approximately 113.4 GW. MISO delivers power across 15 U.S. states and the Canadian province of Manitoba.
Approximately 3.6 GW of new capacity additions were offered into the auction for this winter season. Natural gas resources led those additions. Coal, wind, solar and battery storage additions supported them. Imports from neighboring systems rose by roughly 1 GW. Suspensions and retirements reduced available capacity by 2.3 GW.
Tim Aliff, MISO’s executive director of market operations, said preparation for winter starts well before temperatures drop. He said the assessment reflects work by MISO and its member utilities to bring new resources online. That work includes planning for a range of operating conditions through the season.
Aliff also named the risks. “Our region enters this winter season with sufficient capacity to meet forecasted demand, but reliability is never something we take for granted,” he said. He pointed to tighter reserve margins, steep evening ramp periods and the potential for large winter storms. T&D World reported that MISO identified those three factors as possible operational challenges despite the projected capacity surplus.
The National Oceanic and Atmospheric Administration expects above-normal temperatures across much of the MISO footprint this winter. NOAA forecasts temperatures in the South Region closer to seasonal norms. It also projects above-normal precipitation in the South Region and below-normal precipitation across portions of the Great Lakes.
The projected peak is higher than a year ago. In November 2025, MISO expected peak winter demand of around 103 GW for the 2025-2026 season, Great River Energy reported at the time. The operator said then that demand could reach as high as 109 GW. The winter before that, MISO reached a peak of 108 GW on January 21, 2025, during Winter Storm Enzo. The release does not say what drives the higher forecast for this winter.
MISO presented the assessment at a stakeholder workshop on October 28 at 2 p.m. ET. The operator said it and its member utilities run seasonal assessments, winter preparedness drills and training exercises before each season. The release does not break the capacity offers out by fuel or by zone. It also does not state how much accredited capacity cleared the auction for the winter season.
Why It Matters
Capacity offers are not the same as capacity that shows up on a cold morning. The 2.3 GW of suspensions and retirements matter when one storm covers several states at once. So do the reliance on imports and the gas-led mix of the 3.6 GW of additions. The evening ramp that Aliff named is the window when solar output falls. Gas, coal and storage must then carry the load.
The projected peak of about 113.4 GW also sits above the roughly 103 GW MISO expected a year ago. It is also above the peak demand of 108 GW that MISO reached during Winter Storm Enzo. For utilities and large loads in the footprint, the figure to watch is not the approximately 134.7 GW of winter capacity offers. It is how much of that capacity is accredited, fueled and weatherized when the first cold snap arrives.
Critical Perspective
MISO’s 134.7 GW is a count of offers into the Planning Resource Auction, not accredited capacity proven to perform at 6 a.m. in a January storm. The 108 GW peak during Winter Storm Enzo in January 2025 landed above the roughly 103 GW MISO expected for the following winter, so a 113.4 GW projection is a forecast, not a ceiling. The release books roughly 1 GW of extra imports from neighbors who face the same cold fronts, and it removes 2.3 GW of suspensions and retirements without naming a single unit. With natural gas leading the 3.6 GW of additions, how much of that fleet holds firm fuel on the coldest morning, and why does an assessment that flags steep evening ramps publish no reserve margin figure at all?
Sources
- MISO: MISO releases winter readiness assessment for the 2026-2027 season (Oct. 28, 2026)
- T&D World: MISO Reports Sufficient Capacity for Winter 2026-2027 (Oct. 30, 2026)
- American Public Power Association: Midcontinent ISO Releases Winter Readiness Assessment (Oct. 28, 2026)
- Great River Energy: MISO says power grid ready for winter, but stresses risks remain (Nov. 19, 2025)
