Three of the largest power-market operators in the country broke their all-time peak demand records this summer. PJM reached 162.6 gigawatts on July 2, ERCOT in Texas hit 91.1 gigawatts on July 22, and the Southwest Power Pool peaked at 58.0 gigawatts on July 27. All three figures topped records that had stood for between one and three years.
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The U.S. Energy Information Administration published the tally on Oct. 15 in its Today in Energy series, with Alex Mey as principal contributor. The numbers come from hourly reports that grid operators file with the agency, and they show how much strain a hot summer put on three very different regional systems at nearly the same time.
PJM, ERCOT and SPP set new peaks
The EIA analysis lists each new record against the one it replaced. PJM, which coordinates power across a large swath of the Mid-Atlantic and Midwest, beat the 160.6 gigawatts it set on June 23, 2025. ERCOT, which runs most of the Texas grid, topped 85.5 gigawatts from Aug. 20, 2024, a margin of about 5.6 gigawatts that is the widest of the three in absolute terms. The Southwest Power Pool, which spans parts of the central United States, passed the 56.0 gigawatts it recorded on Aug. 21, 2023.
EIA says most of these peaks occurred during regional heat waves. The agency places the records inside the hottest summer on record nationally, a claim it supports with a Fox Weather report on the season. Air conditioning is the largest swing factor in summer electricity use, so when a heat wave settles over a region, demand climbs on the same afternoon across millions of homes and businesses. The peak hour, rather than the seasonal average, drives how much generation and transmission a region must have ready, because a grid operator has to cover that single hour even if demand is far lower for the rest of the year. Each of the three records was set in July, the month when cooling load typically runs highest.
Operators that came close but fell short
Not every region cleared its own bar. EIA reports that California’s grid operator, CAISO, reached 50.0 gigawatts on Sept. 9 against a record of 51.1 gigawatts set on Sept. 6, 2022, while ISO New England peaked at 25.3 gigawatts on July 2 compared with its 25.9 gigawatts record from June 24, 2025. New York’s operator reached 31.1 gigawatts on July 2, below the 31.9 gigawatts it logged on June 24, 2025 in EIA’s hourly data, although the operator itself reports a larger 34.0 gigawatts from 2013, before the agency began collecting hourly figures.
The Midcontinent Independent System Operator reached 121.5 gigawatts on June 30, the highest value in EIA’s grid monitor but below the 127.1 gigawatts MISO reported on July 20, 2011. EIA describes CAISO and ISO New England as within roughly 2% of their records, New York within 3% and MISO within 4%.
Several of those figures landed on the same day. July 2 produced the PJM record and also the summer peaks for ISO New England and New York, so one date accounts for a record in one region and near-records in two neighbors. The ERCOT and Southwest Power Pool records came weeks later, on July 22 and July 27, which means the three new all-time highs were set on three separate days rather than in a single event. California’s peak came latest of all, in September, well after the others had passed.
Form EIA-930 data and its limits
All of the figures come from Form EIA-930, which feeds the agency’s Hourly Electric Grid Monitor. Balancing authorities report that data as-is, meaning the values are each operator’s best numbers at the time of reporting. EIA cautions that reporting issues can limit data quality and that figures published by an operator itself may differ from what appears in the form, which is why the MISO and New York comparisons carry footnotes about records set before hourly collection began.
The regional groupings are also worth understanding. EIA keeps a reference page on the country’s wholesale electricity markets, where regional transmission organizations such as PJM, ERCOT and the Southwest Power Pool are mapped. The Southwest Power Pool also publishes its own fast facts page that lists prior peak figures for its footprint.
The records matter beyond trivia. Each new peak sets a higher benchmark that planners must meet in coming years, and EIA has also covered the Texas peak in an earlier Today in Energy article. Whether next summer produces another round of records will depend largely on the weather, since the EIA piece ties this summer’s peaks to heat waves. A milder season could leave the new marks standing for years. The 2026 values are the best numbers operators had at the time of reporting, so small revisions to individual figures remain possible.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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