Summer 2026 in Review: Record Heat, Record Power Demand

Summary

ERCOT set a new all-time peak demand record of 91.1 GW even without the extreme temperatures seen in prior record-setting years.

Relentless heat in Europe left residents sweltering, which will continue to push air conditioning demand higher in the future.

Markets with significant solar and battery penetration weathered summer heat more smoothly, highlighting how storage is reshaping price risk and grid reliability.

What a summer. A massive heat ridge parked itself over the Four Corners and Texas for weeks, the East flipped between cool stretches and brutal heat, and Europe had its hottest summer on record. Even the tropics had a split personality: the Atlantic stayed completely quiet while the Pacific is still churning out a record season.

For traders, that meant volatility almost everywhere you looked. Here's how the season played out across the major markets, where demand hit its limits, and how our forecasts held up when it mattered most.

The Big Picture: Heat, Drought, a Building El Niño, and a Quiet Atlantic

The West and South ran hot all summer thanks to a persistent ridge over the Four Corners and Texas. Out East, it was a different story. A few weeks ran below normal, then 1 to 2 weeks came in 15-20°F above normal. Those swings are exactly what make or break a trading week.

Drought is also a major factor heading into fall, especially across the southern Plains, the upper West, and the Four Corners. On top of that, El Niño strengthened all summer and has now reached "Super El Niño" territory. That same pattern helped keep the Atlantic shut down, with strong wind shear stopping storms from organizing, while the Pacific had one of its most active seasons ever. Could this Super El Niño lead to a warmer winter overall?

ERCOT: A New Peak Demand Record

ERCOT set a new all-time peak demand record of 91.1 GW on July 22, and August followed with a handful of days above 90 GW. Interestingly, temperatures weren't dramatically and consistently hot like what we saw the summer of 2022, but we still saw a typical Texas summer, which tells you how much structural demand growth is driving these peaks.

Even so, prices stayed relatively calm. Solar carried the grid through the hottest hours, and batteries picked up the evening ramp as the sun went down, right when the grid used to get into trouble.

Amperon’s day-ahead forecast settled with a 0.18% APE at the peak hour, HE18, where we set the new demand record, compared to ERCOT’s 2.31% APE. ERCOT was forecasting a much stronger falloff after HE17 than what actually occurred, leaving traders short if they were solely reliant on ERCOT’s day-ahead forecast on the ISO’s biggest day ever!

PJM: The Record That Almost Was

PJM saw its hottest temperatures of the summer during the week of July 4th, with highs reaching above 100 and "feels like" temperatures reaching as high as 115F in some regions due to the humidity.

PJM peak demand hit 162.2 GW, and it could have broken the all-time record of 165.56 GW if demand response and curtailments hadn't come into play. Accounting for 3-5 GW of DR and curtailments, the underlying demand was well above what showed up in the final number.

Unlike ERCOT and CAISO, PJM doesn't have a large fleet of renewables or batteries to lean on, and it showed in real-time prices. Around 8pm on July 2 when real time prices were peaking the most, less than 5% of PJM’s supply came from wind, solar, batteries, and hydro combined.

With data center demand growing fast and generation additions not keeping up, this is a market to watch closely. We have already seen years of historic capacity pricing for PJM. This will continue as long as we see this load growth trend keep up.

MISO and SPP

This summer, MISO demand reached 125.1 GW on June 30, the highest demand we have seen in at least 10 years and right in line with MISO’s predicted peak. Amperon’s APE at HE17, the peak demand hour, was 0.70% compared to the ISO’s 0.92%. SPP also broke its 2023 demand record with load reaching 57.6 GW on July 27.

Demand growth in these regions is also very prominent, but the supply stack is also growing.This summer, MISO nearly doubled its solar capacity year over year, which led to MISO starting to change how it manages steep net demand shifts. The ISO still saw very negative DARTs across the summer’s demand peak on June 30. With the duck curve deepening, MISO is starting to look a lot more like CAISO and ERCOT.

Parts of MISO Central also saw a record-breaking amount of severe weather this summer. Illinois recorded its most tornadoes in a year on record, with a large concentration of them in June. While SPP is typically considered the heart of Tornado Alley, this summer was a different story.

Classic California Late-Summer Heat

This summer ran warmer than the last few in California. In true California fashion, the biggest heat arrived late, with demand reaching 49.9 GW on September 9. That's the highest demand CAISO has seen since 2022, and it was within striking distance of the 52 GW record.

Solar and batteries played a huge role in keeping the grid stable through that event. While natural gas plants were supplying about 45% of supply during the peak demand hour of the day, solar generation was still going strong, providing about 20% of power while we started to see batteries ramp up at this time to capture 10% of load.

At the peak price hours, when we saw about 15 minutes of negative DARTs, batteries supplied a record-breaking 22% of grid demand, while wind and hydro contributed another ~10%.

Europe: The Hottest Summer on Record

The EU and the UK saw an incredible number of 90-100°F (32-38°C+) days this summer. Europe got an early warning in May, when a heat dome shattered records in several countries. London hit 35.1°C (95.2°F) on May 26, beating its previous May record by 2.3°C.

And that was just the start. By mid-August, Western Europe was in its fifth heat wave of the season, with temperatures well above 40°C (104°F) across a wide area. Bordeaux broke its all-time high three days in a row in June, peaking at 42.5°C on June 24, and Slovakia set new national records for both daytime and nighttime highs in August. The combined June and July temperatures in Western Europe were the highest on record.

What made this summer especially tough for power markets was how relentless the heat was (just as Amperon predicted). Heat waves lasted days and sometimes weeks, and temperatures stayed high overnight, so there was very little relief. The heat also worsened a drought that has gripped the region for months, pushing major rivers to record-low levels and disrupting water and power supplies along with transportation routes.

It's worth noting how different Europe's demand picture is from the U.S. Only about 23% of European homes have air conditioning, compared to 90% in the U.S., so the grid's response to heat looks very different—but that gap is likely to keep shrinking as more cooling gets installed.

Tropics: Quiet Atlantic, Record Pacific

There were minimal hurricanes in the Atlantic this season: Atlantic storms are only at letter G, while the Pacific is already at P! Strong wind shear kept Atlantic storms from organizing, which was great news for Gulf Coast gas and power infrastructure.

The Pacific, on the other hand, had a record season. So far, there have already been 6 major hurricanes, with Major Hurricane Polo being one of the strongest-ever storms in the Eastern Pacific. This compares to just ~4 major Pacific hurricanes in an average year, and we are not out of the woods yet, with Pacific sea surface temperatures still sitting far above normal.