MISO’s seasonal coincident peak (CP) marks the highest demand interval of the season. September 1st kicked off the Fall CP season, and Amperon was ready.
A full seven days out, Amperon’s Peak Alerts started flagging Monday, September 15th as the day to watch with an expected peak of at least 101 GW and a likelihood score of 94 out of 100. By the time the day-ahead CP call came on Sunday morning (08 UTC), Amperon held steady with a score of 95 for September 15th. This was reaffirmed at the intraday call the next day, with another score of 95 at 12pm (16 UTC). Two independent Amperon calls, both locked in for the 15th.
Calling MISO's Fall 2025 CP Day
Other days that week were also assigned CP scores above 90 due to elevated demand, combined with uncertainty around curtailments and demand response. Still, Monday the 15th is most likely to settle as the official Fall 2025 CP day. Even though MISO’s CP day isn't confirmed until November, demand most likely won't break 100 GW for the rest of fall. The average peak load for September in 2024 was 90 GW. Those numbers drop significantly as cooler, fall-like temperatures roll in, lowering demand. For October, the 2024 average peak was 65 GW. For November, the 2024 average peak was 63 GW.
During this stretch, Amperon also outperformed MISO’s forecast. At the peak hour on September 15th, Amperon’s APE was 1.08% compared to the ISO’s APE of 3.57%. Across the four peak days, Amperon achieved a 1.63% MAPE on peak hours, with September 18th delivering a near-perfect 0.01% MAPE (using forecasts published at bid close the prior day). By comparison, MISO’s forecasts produced a 3.26% MAPE over the same peak hours, with consistent overforecasting of peak demand by 3–4 GW. This led to extremely positive DARTs across the evening of what looks to be the Fall CP day.
MISO’s fall CP season is not even halfway finished. To make sure you have the most accurate peak alerts for this season and next, reach out to Amperon.
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