Extreme US heat wave boosts power prices, demand as temps reach 100 F

A major heat wave moving across the US July 2 sent power prices and demand soaring, with power grid operators issuing energy alerts, warnings and other measures.

PJM Interconnection issued a hot weather alert and pre-emergency actions.

"A Hot Weather Alert remains in effect for the entire region PJM serves through at least July 3," the grid operator said in a statement. "A Hot Weather Alert is an established procedure PJM issues ahead of forecasted hot weather and/or high humidity to prepare transmission and generation personnel and facilities for expected increases in electricity demand, or load."

A pre-emergency load management reduction action has also been issued.

Real-time power prices in the Dominion Zone had reached $989.60 per megawatt hour as of early afternoon ET July 2.

Power demand was forecast to reach 166,241 megawatts July 2, with the record peakload of 165.6 gigawatts set Aug. 2, 2006.

Temperatures in Philadelphia had reached 100 F by early afternoon and were forecast to hit 103 F, according to the National Weather Service. Temperatures in the Pennsylvania city were forecast to reach 104 F July 3.

PJM Interconnection was scheduled to export 1.134 GW to the Midcontinent System Operator footprint, but instead was actually importing 1.352 GW from MISO as of 1:50 pm ET, according to PJM data.

Imports from the New York Independent System Operator into PJM remained close to scheduled levels at around 700 MW.

NYISO issued an energy watch for July 2 due to a decline in operating reserves, but said the "grid is operating normally at this time, and there are adequate resources to meet forecast demand."

Real-time power prices rose above $1,000/MWh in New York City Zone J and Long Island Zone K for some pricing intervals but then retreated to $182.37/MWh and $176.35/MWh, respectively, by early afternoon.

Temperatures in New York City reached 100 F around that time.

Power demand was forecast to reach 32,197 MW, close to the record peak of 33,956 MW set on July 19, 2013.

At times during the afternoon, the newly constructed 1,250-MW Champlain Hudson Power Express transmission line was running at full capacity. Transmission Developers, backed by private equity firm Blackstone, developed CHPE. The project began construction in November 2022 and is supplied with hydropower from provincially owned Hydro-Québec's reservoir system.

"New York State is in the midst of a prolonged heat wave, and we've been carefully monitoring our electrical grid to ensure it is able to withstand the increase in energy usage and keep New Yorkers safe," Governor Kathy Hochul said in a statement.

"My team has been coordinating with Con-Ed, NYISO and New York City leaders to ensure all large consumers able to switch to other fuel sources have done so to reduce their usage," Hochul said. "Due to the increase in energy demand and unexpected load challenges, I am also calling on New Yorkers to do their part to proactively conserve electricity if safe to do so by setting air conditioning units between 75-78 degrees [F] and avoiding unnecessary appliance use."

Additionally, ISO New England said it is expecting "exceptionally tight operating conditions" on the regional electric grid over the evening peak July 2.

"While current system forecasts show the region able to meet expected consumer demand and required operating reserves, there is little surplus generating capacity available to deal with unanticipated events. 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," the grid operator said.

ISO-NE Mass Hub on-peak day-ahead power prices for July 2 averaged $424.64/MWh when temperatures were forecast to reach 97 degrees Fahrenheit in Boston. Connecticut Hub on-peak day-ahead power prices averaged $415.08/MWh July 2, when temperatures in Hartford were forecast to reach 100 F.

Last summer's power demand peaked at 26,586 MW on June 24, 2025. All-time peak power demand reached 28,130 MW on Aug. 2, 2006.