July 30, 2025

Monthly wholesale electricity prices and demand in New England, June 2025

Wholesale power prices averaged $47.56 per megawatt-hour (MWh) in the Real-Time Energy Market in June 2025, up 54% compared to the previous year.¹ Day-Ahead Energy Market averages were $43.75/MWh, up 25% from June 2024.

By the numbers

June 2025 and Percent Change from June 2024 and May 2025	June 2025	June 2024	May 2025
Average Real-Time Electricity Price ($/megawatt-hour)	$47.56	+53.9%	+45.1%
Average Natural Gas Price ($/MMBtu)	$2.89	+50.5%	+13.3%
Peak Demand	26,551 MWs	+9.9%	+81.4%
Total Electricity Use	9,972 GWh	−1.4%	+18.9%
Weather-Normalized Use²	9,506 GWh	−1.6%	+11.2%

Drivers of wholesale electricity prices

In general, the two main drivers of wholesale electricity prices in New England are the cost of fuel used to produce electricity and consumer demand.

Power plant fuel

Fuel is typically one of the major input costs in producing electricity. Natural gas is the predominant fuel in New England, used to generate 55% of the power produced in 2024 by New England’s power plants, and natural-gas-fired power plants usually set the price of wholesale electricity in the region. As a result, average wholesale electricity prices are closely linked to natural gas prices.

The average natural gas price during June was $2.89 per million British thermal units (MMBtu).³ The price was up 51% from the June 2024 average Massachusetts natural gas index price of $1.92/MMBtu. The Mass. index price is a volume-weighted average of trades at four natural gas delivery points in Massachusetts, including two Algonquin points, the Tennessee Gas Pipeline, and the Dracut Interconnect.

Wholesale electricity and natural gas prices

Electricity demand

Demand is driven primarily by weather, as well as economic factors. Energy usage during June decreased 1.4% to 9,972 GWh from the 10,117 GWh used in June 2024. The average temperature during June was 69˚ Fahrenheit (F) in New England, down 2˚ from the previous June. The average dewpoint, a measure of humidity, was 58˚F in June, the same as the previous June. There were 79 cooling degree days (CDD) during June, while the normal number of CDD in June is 47 in New England.⁴ In June 2024, there were 81 CDD. There were 40 heating degree days (HDD) during June, while the normal number of HDD in June is 50 in New England. In June 2024, there were 5 HDD.

Consumer demand for electricity for the month peaked on June 24 during the hour from 5 to 6 p.m., when the temperature in New England was 97°F and the dewpoint was 67°F. Demand reached 26,551 MW. The June 2025 peak was 9.9% higher than the June 2024 peak of 24,166 MW, set during the hour from 4 to 5 p.m. on June 20, when the temperature was 91°F and the dewpoint was 70°.

Peak demand is driven by weather, which drives the use of heating and air conditioning equipment. The all-time high winter peak was 22,818 MW, recorded during a cold snap in January 2004 when the temperature was −1°F and the dewpoint was −20°F. The all-time peak demand in New England was 28,130 MW, recorded during an August 2006 heat wave, when the temperature was 94°F and the dewpoint was 74°F. Air conditioning use is far more widespread than electric heating in New England, so weather tends to have a relatively greater impact on the summer peak than the winter peak.

Monthly peak demand and total and weather-normalized energy use

Resource mix and emissions

The mix of resources used in any given time period depends on price and availability, as well as supplemental resource commitments needed to ensure system stability. Natural-gas-fired and nuclear generation produced about 78% of the 9,864 GWh of electric energy generated within New England during June, at about 54% and 24%, respectively. Renewable resources generated about 13% of the energy produced within New England, including 4.3% from wood, refuse, and landfill gas; 2.8% from wind; and 5.4% from solar resources. Coal resources generated 0.2% while oil-fired resources generated 0.7%. Hydroelectric resources generated 7.2%. The region also received net imports of about 256 GWh of electricity from neighboring regions.

The mix of resources used to produce the region’s electricity is a key driver of carbon dioxide (CO₂) emissions. The ISO estimates these emissions through an analysis that blends data on electricity generation by fuel type with an emissions factor for each fuel that is based on data from the Environmental Protection Agency.⁵

June estimated CO₂ emissions in New England, by fuel source (metric tons)

New England power plants produced an estimated 2.77 million metric tons of CO₂ in June 2025, an approximately 4% increase from the previous June.

Estimated CO₂ emissions from natural-gas-fired plants—typically the region’s largest source of power system emissions, due to the significant amount of electricity these resources produce—increased year over year, rising from 2.07 million metric tons to 2.10 million metric tons. These resources accounted for 76% of the power system’s total emissions.

Together, oil- and coal-fired resources produced an estimated 84,977 metric tons of CO₂ in June 2025 (about 3% of the total), up from an estimated 28,167 metric tons in June 2024. Because the region’s wholesale electricity markets select the lowest-priced resources needed to meet demand, oil- and coal-fired resources tend to run more frequently when natural gas prices rise, and less frequently when natural gas prices are low.

CO₂ emissions from other resources—mostly refuse and wood—were estimated at 579,915 metric tons, a 3% increase from June 2024. These resources accounted for about 21% of the power system’s estimated CO₂ emissions for the month.

Estimated year-to-date emissions through June 30 increased 3% year over year, which was largely driven by a colder winter, increased demand, and higher natural gas prices resulting in more oil- and coal-fired generation. Regional CO₂ average annual emissions from electric generation have declined significantly in the last decade. The ISO New England Electric Generator Air Emissions Reports provide a more comprehensive analysis of New England electric power generator air emissions and a review of relevant system conditions.

June year-to-date estimated CO₂ emissions in New England, by fuel source (metric tons)

1. One megawatt (MW) of electricity can serve about 750 to 1,000 average homes in New England. A megawatt-hour (MWh) of electricity can serve about 1,000 homes for one hour. One gigawatt-hour (GWh) can serve about 1 million homes for one hour.

2. Weather-normalized demand indicates how much electricity would have been consumed if the weather had been the same as the average weather over the last 20 years.

3. A British thermal unit (Btu) is used to describe the heat value of fuels, providing a uniform standard for comparing different fuels. One million British thermal units are shown as MMBtu.

4. A degree day is a measure of heating or cooling. A zero degree day occurs when no heating or cooling is required; as temperatures drop, more heating days are recorded; when temperatures rise, more cooling days are recorded. The base point for measuring degree days is 65 degrees. Each degree of a day’s mean temperature that is above 65 degrees is counted as one cooling degree day, while each degree of a day’s mean temperature that is below 65 degrees is counted as one heating degree day. A day’s mean temperature of 90 degrees equals 25 cooling degree days, while a day’s mean temperature of 45 degrees equals 20 heating degree days.

5. The factors used to calculate estimated CO₂ emissions were updated in September 2024. ISO New England analysts regularly review and refine the methodology used to develop these emissions factors, in order to reflect the characteristics of New England’s generating fleet and improve the accuracy of the estimates.