Power demand on the PJM Interconnection — the largest U.S. electricity grid — was forecast to surge to about 141 gigawatts on Friday, coming close to its all-time winter peak, as extreme cold weather tightened energy supplies across the eastern United States.
PJM, which serves 67 million people across 13 Midwestern and Mid-Atlantic states and Washington, D.C., has been under intense scrutiny due to the rapid growth of data centers, whose electricity needs are rising faster than new power generation can be built.
The grid operator has so far managed a 10-day stretch of freezing temperatures and snowstorms without imposing rolling blackouts, despite significant strain on the system.
About 15 gigawatts of power generation — roughly 11% of PJM’s committed capacity — was unavailable on Friday due to outages, though that was an improvement from earlier in the week when outages exceeded 22 gigawatts.
PJM earlier warned that electricity demand could hit 148 gigawatts, which would have shattered the winter record of 143.7 gigawatts set in January 2025, but forecasts were later revised down as some areas warmed slightly.
The U.S. Department of Energy also asked data centers to run backup generators, helping reduce pressure on the grid during peak demand periods.
Wholesale electricity prices reflected easing stress, with spot prices around $173 per megawatt hour on Friday, sharply lower than the more than $3,000 per MWh seen earlier in the week.
Still, PJM and neighboring grids in New York and New England faced congestion on major transmission lines, driven by surging demand and limited power flows during the cold snap.
Temperatures dipping below minus 18 degrees Celsius (0°F) further strained the system by reducing the operating capacity of power plants and increasing household and industrial power use.
The episode highlights growing concerns that weather extremes and expanding digital infrastructure are pushing U.S. power grids closer to their operational limits, even without record-breaking demand.