Post: PJM outlines hot weather operations

PJM outlines hot weather operations

In June 2025, extreme heat pushed PJM energy demand to the third- and fourth-highest all-time peak loads, the grid operator said.

As noted in a presentation at the PJM Operating Committee the grid at peaked at over 160 GW, the highest peaks in 14 years after hot weather impacted the region June 22–26. PJM anticipated these conditions in its annual summer outlook, noting that demand response could be needed to meet reserve requirements in extreme scenarios. Generator outages were approximately 5GW higher than PJM anticipated in its summer outlook, but PJM maintained its reserve requirements at all times during the June heat wave.

Source: PJM

PJM actions in brief

• The week before the heat wave arrived, PJM required transmission and generation owners to begin deferring scheduled maintenance and return generating units to service to keep critical infrastructure online from June 21 to June 26.
• PJM originally issued a Hot Weather Alert June 19 for the period between June 22 through June 26 to prepare resources for the approaching weather affecting all of the PJM region.
• PJM issued a Maximum Generation Alert for the PJM RTO effective June 23 through June 25. This notifies transmission and generation owners to keep equipment online and to be in a state of readiness to be dispatched, alerts neighboring regions that electricity exports from PJM may be scaled back, and indicates that demand response may be used by PJM operators if necessary.
• The grid operator took Pre-Emergency Load Management Reduction Actions on June 23, 24, and 25 across various zones, including Atlantic City Electric, Baltimore Gas & Electric,  and Dominion. These urgent dispatches, often with just 30 minutes’ notice, highlighted the critical need for rapid and reliable load reductions to maintain grid stability.
• On June 23, the heat wave produced a preliminary hourly peak load of 161,770MW between 5 and 6 p.m.
• The next day (June 24) demand driven by temperatures 95 degrees and higher in many parts of the region produced a preliminary peak load of 162,401MW between 5 and 6 p.m. These represent the third- and fourth-highest peak loads recorded in PJM.
• Thunderstorms with wind on June 25 and June 26 brought cooler temperatures and lower preliminary peak loads of 153,414MW on June 25 and 145,918 MW on June 26.
• PJM successfully deployed demand response resources on June 23 and June 25 in select zones and across the RTO on June 24, helping to reduce load by more than 4,000MW during the most extreme peak loads.

PJM recorded its all-time summer peak load record at 165,563 MW in 2006. PJM’s 2025 Long-Term Load Forecast predicts that summer peak will climb to 220,000MW over the next 15 years. The June 24 peak of over 162,000MW is nearly 10,000MW higher than the 2024 peak and 15,000MW higher than 2023. This is a result of both extreme hot weather and the growing demand from data centers.

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