US regional grid operators scrambled to prevent blackouts as extreme heat gripped the eastern half of the country, causing widespread power generation strain. Temperatures soared past 100 degrees Fahrenheit (38 degrees Celsius), leading to congestion on transmission lines and skyrocketing wholesale electricity prices.
New York City saw peak wholesale prices reach $2,400 per megawatt hour (MWh) during evening demand, with Long Island prices topping $7,000 per MWh. PJM Interconnection, covering one in five Americans, ordered several utilities to curtail power to customers in voluntary reduction programs.
ISO New England, which includes Boston, saw spot wholesale electricity prices soar past $1,500 per MWh on peak consumption around 5:30 p.m. EDT. The grid operator issued a “Power Caution” after an unexpected loss of generation left the region short of resources needed to meet demand and operating reserves.
Duke Energy Carolina was ordered by the US Department of Energy to use specific generating units to operate at maximum output levels in the southeast. As a result, the utility notified some wholesale customers to limit their use, expected to reduce electricity demand by up to 1,000 megawatts during peak hours.
Grid operators and utilities are calling on stand-by units to boost supply and have asked power plant operators not to perform maintenance that could affect reliability. Temperatures in Boston reached 100 F (38 C) early Tuesday afternoon, with forecasted demand approaching 26,000 MW short of the record high set in August 2006.
Source: https://www.reuters.com/business/energy/new-england-electric-grid-operates-under-precautionary-alert-2025-06-24