Heatwave Drives Record Electricity Demand in Eastern U.S. Electricity demand soared across the eastern and midwestern United States in June as an intense heatwave gripped the region. The Eastern Interconnection, which covers the mainland U.S. east of the Rockies excluding Texas, experienced unprecedented electricity consumption, according to the EIA.
On June 21, peak demand reached 502,670 megawatts (MW) in a single hour, surpassing the 2023 June peak of 467,609 MW.
The heatwave brought record-breaking temperatures to several areas. Bangor, Maine, hit 96 degrees on June 20, a record not seen since 1931. In the Philadelphia, South Jersey, and Delaware region, 20 heat records were broken between June 19 and June 24. Similarly, the Baltimore-Washington D.C. area saw record temperatures on June 22 and 23. Such extreme weather conditions significantly drive up electricity demand, particularly for air conditioning.
The Eastern Interconnection comprises multiple Independent System Operators (ISOs) and Regional Transmission Operators (RTOs) that manage electricity dispatch across vast areas. PJM, the Midcontinent Independent System Operator (MISO), the Independent System Operator for New England (ISO-NE), and the New York Independent System Operator (NYISO) were notably impacted by the heatwave.
PJM, which spans from New Jersey to Illinois, saw electricity demand peak at 147,976 MW on June 21, marking a 19% increase from the previous year's June peak. During the heatwave, daily peak demand was between 1% and 24% higher than any June day in the past five years. PJM had forecasted a peak summer demand of 151,000 MW for 2024 and issued multiple alerts from June 17 to June 26 to ensure grid stability and prevent outages.
While MISO's overall demand did not peak, the northern region experienced higher-than-usual demand. Notably, Detroit's temperatures exceeded those in traditionally hotter New Orleans on multiple days. Consequently, northern MISO regions like Wisconsin and Michigan saw higher demand than southern areas.
In the Northeast, ISO-NE's peak demand reached 23,266 MW on June 20, and NYISO peaked at 28,245 MW on June 21. These figures approached last year's summer peaks and the forecasted demands for 2024, with ISO-NE predicting 24,553 MW and NYISO 31,541 MW for the season.