ISO New England has issued a precautionary alert due to tight power grid operating conditions expected during the evening peaks. The grid operator did not declare an emergency but it warned there is little surplus capacity for unexpected events.
“While hot, humid weather drives high demand across the region, neighboring power shortages in New York and Quebec threaten to limit necessary energy imports, leaving little surplus capacity available,” according to an ISO statement released on Friday. “Residents are encouraged to reduce energy usage between 4 p.m. and 8 p.m. to ease stress on the system.”
ISO-New England is the independent, nonprofit corporation responsible for keeping electricity flowing across the six New England states and ensuring that the region has reliable, competitively priced wholesale electricity today and into the future.
The extremely hot and humid weather is also affecting systems to the west and the north, including New York and Quebec, increasing uncertainty regarding energy imports to New England.
All available generating and demand-reducing resources are expected to be operating during the late afternoon and early evening hours.
Consumers across New England can help reduce stress on the power system by limiting their energy use from 4 to 8 p.m., when demand for electricity is typically the highest.
Actions like pre-cooling your home, using major appliances (such as washing machines, dryers, and dishwashers) during off-peak hours, or keeping curtains and blinds closed can help reduce overall system demand.
ISO New England first issued a precautionary alert for all of New England on July 1 due to hot, humid weather across the region and anticipated tight operating conditions over the evening peak on July 2, but did not declare a system emergency
At this time, ISO-NE expects the regional power system will have sufficient resources to meet anticipated demand. While this predicted demand would be the highest so far this year, the projections are in line with the ISO’s forecasts for the summer, as hot weather and high humidity are expected to continue through the holiday weekend.
ISO experienced some of its highest peak electric loads on record during the heat wave, reaching 23,950 MW on Wednesday; 25,850 MW on Thursday; and 24,000 MW on Friday; with 21,950 MW predicted for Saturday.
The all-time highest recorded electricity usage (peak demand) by ISO-NE is 28,130 megawatts (MW). This record was set on August 2, 2006, driven by a prolonged and intense heat wave.
Peak demand is the time when electricity use is expected to be highest. For additional context, 1 megawatt (MW) of electricity can serve about 750 to 1,000 average homes in New England.
While the current temperatures are extremely high, ISO New England isn’t reaching its all-time high MW usage for several key reasons:
Massive Solar Growth: The addition of over 8,000 MW of behind-the-meter (rooftop) solar generation fundamentally alters the grid’s load curve.
Shifted Peak Timing: Because of rooftop solar, the peak hour for grid demand has shifted from mid-afternoon—when the sun is high and AC units run continuously—to the early evening (4 p.m. to 8 p.m.).
Declining Baseline Usage: Despite population growth and increased cooling needs, total annual electricity consumption in New England has generally trended downward compared to the early 2000s, thanks to modern energy-efficiency standards and building upgrades.
ISO New England’s system operators monitor grid conditions around the clock and are well-trained to handle increased seasonal demand, unexpected generation loss, or transmission outages.
The ISO has a range of tools and procedures available to mitigate concerns if system conditions change. For more detailed information, visit the Seven-Day Capacity Forecast page at shorturl.at/GGJGr