A summer heat dome stressed the US Eastern grid, forcing data centers to curtail loads and raising questions about climate-resilience capacity.

PJM, the largest U.S. power grid, braced Thursday for record-setting electricity consumption driven by a heat dome and an accelerating data center boom. Temperatures approaching 100 degrees Fahrenheit (38 degrees Celsius) were forecast to break the system's 20-year demand record around 6 p.m. EDT, with peak consumption projected at 166.2 gigawatts—exceeding the prior record of 165.6 GW. To manage the surge, PJM rerouted massive traffic along power lines and dispatched expensive fossil fuel plants to avert outages. The grid operator said it has adequate capacity to meet the immediate challenge.

The strain on PJM's infrastructure reflects a broader cost crisis. Wholesale power costs surged 68% during the first five months of 2026 to $40 billion, compared with $23.8 billion in the same period last year—an increase of more than $16 billion. Data center demand accounted for $3.8 billion of that increase, or approximately 23% of the total year-over-year rise. Costs to maintain reserve coal and gas plants on PJM's congested grid nearly doubled in the first five months, with so-called uplift payments reaching $1.1 billion from $531 million a year earlier, according to Monitoring Analytics, PJM's independent market monitor.

Heavy power line congestion in northern Virginia—home to the world's largest concentration of data centers—contributed to wholesale price spikes exceeding $2,000 per megawatt hour this week. While such extreme prices do not immediately affect residential monthly bills, sustained elevated wholesale costs will eventually force utilities to pass them on to consumers through higher rates.

PJM has no spare capacity to support new demand beyond next year, according to ICF, a global consulting firm. NYISO, the power grid operator for New York state, could face similar constraints within the coming years. "When the largest grid operator in the country is flagging price spikes and warning on record demand in the same breath, that's a signal homeowners can't afford to ignore," said Trevor Guilday, an energy conservation expert and founder of EcoGen America. "Upgrading insulation, switching to energy-efficient appliances, or installing residential solar aren't just green choices anymore. They're practical financial defenses against a grid that's under real strain."

PJM said it is coordinating with state and federal policymakers to accelerate new generation capacity while managing the integration of data centers and other large loads without disproportionately impacting consumers.