Over 100°F Heat Adding Stress to the AI-laden Grid

Energy News Beat

Back-to-back heat waves sweeping the United States are pushing electricity grids to a tipping point, as temperatures topping 100°F (38°C) drive households to max out air conditioners while a surge in around-the-clock demand from AI data centers and factories shrinks power reserves and strains decades-old transmission equipment.

This is emerging as the new normal for the U.S. power system: seasonal weather extremes colliding with explosive electricity growth from the artificial intelligence sector. Data centers, which require constant power for cooling and computation, are amplifying the pressure that extreme heat has long placed on aging infrastructure.

Grid Operators Under Pressure Across the Country

Major regional transmission organizations have faced repeated tests this summer. In early July, PJM Interconnection—the largest U.S. grid operator, serving about 67 million people across the Mid-Atlantic, Midwest, and parts of the South—set or approached all-time demand records amid triple-digit heat. Forecasts pushed past the previous high of roughly 165,563 MW (set in 2006), with preliminary peaks near or above 166,000–168,000 MW. PJM issued Hot Weather Alerts, Maximum Generation Alerts, and Load Management Alerts; the U.S. Department of Energy granted emergency authority that included directing large loads such as data centers to switch to on-site backup generation. Transmission congestion, including near northern Virginia’s dense data-center cluster, drove up wholesale prices.

ERCOT in Texas shattered its all-time demand record during a mid-to-late July heat wave, reaching a preliminary peak of about 91,308 MW on July 22 (well above the prior mark of roughly 85,500 MW from 2023). The grid operated with substantial reserves and no emergency alerts at the peak, though operators noted the underlying load growth is driven in part by data centers and is projected to climb sharply in coming years. As of July 26, ERCOT reported normal conditions with operating reserves around 14,000 MW.

MISO, covering much of the central U.S., issued multiple Hot Weather Alerts through late July (including on July 24) and has operated under elevated demand from heat indices reaching 110°F or higher in states such as Missouri, Illinois, Indiana, and others. NYISO activated demand-response resources and issued an Energy Watch during early-July peaks near 31,000–32,000 MW. ISO New England and CAISO have generally reported adequate supply, though both monitor extreme heat and, in California’s case, wildfire risks that can constrain transmission. CAISO’s summer assessment indicated sufficient resources under most scenarios, with grid status remaining normal into late July.

Extreme heat warnings continued on July 26 across large portions of the central and eastern United States, with heat indices up to 112°F in multiple states, underscoring that the season’s stress is far from over.

The AI Data-Center Overlay

The heat is landing on a system already absorbing rapid load growth from hyperscale data centers powering AI training and inference. These facilities run 24/7 and can draw tens to hundreds of megawatts each. National forecasts show data-center electricity demand rising sharply—potentially reaching 6–12% or more of U.S. consumption in the late 2020s and far higher shares in concentrated regions such as PJM and ERCOT. BloombergNEF has projected data-center power demand approaching nearly 200 GW by 2035 in some updated scenarios. In northern Virginia and other hubs, data centers already account for a large fraction of local load, contributing to congestion and higher capacity prices.

Grid operators and policymakers have responded with emergency tools, calls for large loads to provide their own generation or flexibility, and longer-term pushes for new natural-gas, nuclear, solar, wind, storage, and transmission capacity. Aging transmission lines and transformers, many decades old, face greater thermal stress under simultaneous high ambient temperatures and elevated flows.

Recommendations for Consumers: Preparing for Potential Disruptions

While most systems have so far avoided widespread controlled outages, reserves tighten during prolonged heat, raising the risk of localized interruptions or conservation calls. Consumers can take practical steps:

• Conserve during peak hours (typically late afternoon to early evening, often 2–8 p.m. or as directed by your utility): Raise thermostats to 78°F if health permits, use fans, close blinds against the sun, and delay running dishwashers, clothes dryers, ovens, and other large appliances.
• Prepare an outage kit: Stock water (at least one gallon per person per day), non-perishable food, flashlights and batteries (avoid candles), a first-aid kit, fully charged power banks, and any needed medications or medical-device backups. Keep refrigerators and freezers closed as much as possible during an outage.
• Stay informed and connected: Sign up for utility text/email alerts and monitor local grid-operator or National Weather Service updates. Know the location of nearby cooling centers.
  Generator and backup safety: If using a portable generator, operate it outdoors only, far from windows and doors, and never indoors or in attached garages. Consider battery storage systems where feasible.
• Protect vulnerable household members: Check on elderly neighbors, children, and pets. Limit outdoor activity during peak heat and hydrate frequently.
  Longer-term resilience: Explore energy-efficiency upgrades, smart thermostats, or community solar/storage options that can reduce both bills and grid stress.

Utilities often issue voluntary conservation requests before escalating to mandatory measures. Following them helps keep the system stable for everyone.

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