All-Time Hot Summer Causes Three RTOs to Set Peak Hourly Load Records

---

Written by Paul Wiseman for IIR News Intelligence (Sugar Land, Texas)

---

Summary

Three U.S. regional transmission organizations set peak load records in June-August 2026.

---

Summertime Blues

According to the National Oceanic and Atmospheric Administration (NOAA), the average temperature contiguous U.S. (CONUS) 2026 meteorological summer, June-August, was the hottest on record. It surpassed the previous record, set in 1936 and tied in 2021, by 0.4°.

With this added to the growth of data centers and electric vehicle (EV) charging stations, it is no surprise that the U.S. Energy Information Administration (EIA) reports that three regional transmission organizations (RTOs) set all-time peak load records during that time. All other RTOs approached load records this summer as well.

With all this load growth, new power generation will be needed. Industrial Info Resources data show 229 U.S. power generation projects with completion dates in 2026-2035.

By the Numbers

• 3: Number of RTOs that set all time high load records in Meteorological Summer (June-August) 2026
• 0.4°: Amount higher U.S. mainland temps were in Meteorological Summer 2026 than the previous record

The three RTOs setting new records were: the Electric Reliability Council of Texas (ERCOT), which covers 75% of the land and 90% of the load in Texas, 27 million customers; PJM, which includes all or parts of 13 eastern states and the District of Columbia, including 67 million customers; and Southwest Power Pool (SWPP), which covers all or part of 17 states in the south, Midwest and Mountain West, about 20 million customers.

Here is the EIA's list of record-setting peak load dates, previous records and amounts:

• PJM peaked at 162.6 gigawatts (GW) on July 2, 2026, 1.3% higher than the pre-2026 peak of 160.6 GW on June 23, 2025.
• ERCOT peaked at 91.1 GW on July 22, 2026, 6.5% higher than the pre-2026 record of 85.5 GW on August 20, 2024.
• SWPP peaked at 58.0 GW on July 27, 2026, 3.5% higher than the pre-2026 peak of 56.0 GW on August 21, 2023.

The EIA notes that most peaks occurred during regional heat waves. Also of note is that two of the three, ERCOT and SWPP, occurred in August, which NOAA says was the hottest month ever, and at 74.4° was 3.0° hotter than the average across 132 years of data.

Will This El Niño Set More Records?

The 2026-27 El Niño is projected to be by far the strongest one in recorded history, so it is expected to affect North American weather--but not for summer 2027.

That's because it should peak in December 2026, with effects tapering off by early 2027, according to NOAA projections. Should it indeed bring a warm winter to the U.S., it could then, ironically, actually bring lower-than-normal heating costs to many regions.

Keeping Up with the Jones for More Power

Fortunately, as grid demand rises, so does power generation. The EIA says 2025 was a record year for U.S. power generation. "In 2025, the United States generated 4.43 thousand terawatt-hours (TWh) of electricity, up 2.8% from 2024 generation, which previously had been the highest annual total in our Monthly Energy Review Data Browser dataset dating back to 1949," it reported in March of 2026.

Of course, generation is only half of the equation. That power must be delivered to consumers, meaning the grid must also keep up.

In a July 2025 report, Bank of America predicted U.S. electricity demand would grow at a 2.5% compound annual growth rate (CAGR) through 2035, which is many times the 0.5% CAGR seen from 2014-2024. The bank's analysts recommended more spending to update and replace aging infrastructure, and also recommended speedier permitting.

PJM is addressing its challenges. In February of this year, it recommended $12.2 billion in improvements, mainly to improve reliability. It has also instigated measures designed to speed large load and generation connections.

ERCOT in December 2025 implemented what it calls Real-Time Co-optimization Plus Batteries (RTC+B). This is aimed at giving ERCOT the tools to make more timely and efficient use of its five Ancillary Services to meet and economize loads. Ancillary Services include "Regulation (Regulation Up, Regulation Down), Responsive Reserve Service (RRS), Non-Spin Reserve Service (Non-Spin), and ERCOT Contingency Reserve Service (ECRS)," according to the ERCOT website.

And in November 2025 SWPP approved $8.6 billion of Integrated Transmission Plan (ITP) projects, which include new and upgraded high-voltage lines.

Key Takeaways

• Record demand tied to both system growth and all-time heat records led to record peak demand in three U.S. RTOs this year.
• This emphasizes the need for grid investment in both generation and delivery.

---

About Industrial Info Resources
Industrial Info Resources (IIR) is the leading provider of industrial market intelligence. Since 1983, IIR has provided comprehensive research, news and analysis on the industrial process, manufacturing and energy related industries. IIR's Global Market Intelligence (GMI) helps companies identify and pursue trends across multiple markets with access to real, qualified and validated plant and project opportunities. Across the world, Industrial Info Resources is tracking over 250,000 current and future projects worth $30.2 trillion (USD).