Barely a week after clearing one summer heat wave, the MISO grid rolled straight into another. Through the middle of July, cities across the Midwest climbed into the 90s. As Figure 1 shows, average Midwest temperatures spent several days well above normal, peaking midweek before the pattern began to ease. This was not a brief warm spell but a sustained stretch of heat that kept building day after day. As with the previous event, the heat was widespread rather than local, pressing on neighboring grids to the east at the same time and raising the competition for power across the region.

Figure 1 | Average Midwest Temperatures and Differences from Normal (June & July 2026)

With that heat came a rapid climb in demand. MISO system load pushed above 117 GW early in the week and peaked at 120 GW on the hottest days, approaching the levels seen during the prior heat wave. The real strain, however, came from the combination of high load and weak renewable support. Wind generation ran thin throughout the event, at times averaging under 4 GW during the critical evening hours, and solar faded just as the evening ramp set in. That left the grid facing a steep climb into the peak, with net load surpassing 109 GW on the tightest day. Figure 2 lays out the MISO market summary, showing how forecasted and actual load, wind, and solar came together to produce one of the tightest ramp periods of the summer so far.

Figure 2 | MISO Market Summary – Forecasts and Actuals (July 13 – 20, 2026)

Conditions grew tight enough that MISO was forced to take emergency action. Midweek, the grid operator declared a Maximum Generation Event Step 1, then escalated it to Step 2, citing forced generation outages, above normal temperatures, and load coming in higher than forecast. The declaration triggered emergency tier pricing across the North and Central regions during the afternoon and evening hours. Prices responded in kind. Day-ahead peaks settled in the $800 to $900/MWh range for the evening peak hour, and real-time prices popped above day-ahead values in the afternoon and evening as the grid worked through its emergency procedures. For the tightest nights MISO leaned on every tool available to keep pace with the heat-driven demand.

Heat events like this one move fast, and the market impacts can shift by the hour. Energy GPS covered this event in real time through our MISO power market flashes. To stay ahead of the next summer test and receive timely analysis when the grid comes under pressure, subscribe to Energy GPS's MISO power market flashes and system message alerts. Contact us to learn more about subscription options.

Contact Us

Follow us on LinkedIn