Summer has arrived in force across the PJM footprint. A second major heat dome settled over the Northeast and Mid-Atlantic this week, the latest in a run of hot stretches that has pushed the grid to the top of its range again and again. The first event of the summer, over the June 29 to July 3 window, drove metered RTO demand to roughly 162.2 GW on July 2, the strongest reading of the year to that point. This week's dome has been every bit its equal, with widespread heat driving PJM load to just under 160 GW on July 15, nearly matching the early-July high and stringing together another multi-day run of elevated load.

Those numbers are not just weather. They sit on top of a demand base that keeps climbing. PJM's metered summer peak has risen from about 147.8 GW in 2022 to 152.6 GW in 2024 and 160.2 GW in 2025, and the 162.2 GW already set this July is up another 1.3% over last year with the season only half over. Figure 1 shows the relationship between temperature and evening load in PJM, and the upward drift from year to year is unmistakable. A given hot afternoon simply pulls more megawatts onto the system than it did a year or two ago, driven in no small part by data center growth across the Mid-Atlantic and Ohio Valley.

Figure 1 | PJM Daily Average HE18-20 Load versus Philadelphia Temperature

The present heat and the pressure the load growth and the pressure they are putting on PJM capacity were the topic of our latest PJM Power Market Flash, which discusses why the capacity market has been sending the signals it has. Earlier this week on July 14, PJM posted the results of its 2028/2029 Base Residual Auction. The RTO cleared at $325 per MW-day, landing at the FERC-approved collar cap for a second straight auction and easing just 2.5% from the $333.44 result for 2027/2028. Figure 2 places the outcome in the context of a market that has climbed from under $30 per MW-day only two delivery years ago.

Figure 2 | PJM Base Residual Auction RTO Clearing Price by Delivery Year, with the Actual 2028/2029 Result Posted July 14

The auction procured 138,318 MW of unforced capacity, up about 3,700 MW from the prior year, yet it still finished 6,831 MW short of the reliability requirement. That marks a third consecutive delivery year in which cleared supply plus fixed resource commitments failed to reach the one-in-ten standard, leaving PJM with a reserve margin near 14.7%. Demand is arriving faster than new resources can be built, and the price cap keeps the clearing number from fully reflecting how tight the balance has become.

Heat, record load, and a persistent capacity shortfall are three views of the same picture. As the second heat dome of July tests the grid in real time, the auction three years out is wrestling with the same question, and for now the gap between what PJM needs and what the market can deliver remains open.

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