Hot weather updates: Week of June 23, 2025

June 23, 2025 – 9 p.m. 

ISO New England has issued a precautionary alert as hot, humid weather across the region could lead to tight operating conditions on Tuesday, June 24. This is not a system emergency. 

Known as an M/LCC2, this alert notifies power system operations, maintenance, construction, and test personnel, as well as other market participants, that they should suspend any testing or maintenance on their resources that could affect grid reliability. 

ISO New England continues to monitor system conditions and will provide further updates, as needed, in this space. 

June 23, 2025 – 1:30 p.m. 

ISO New England is monitoring system conditions as hot, humid weather drives higher consumer demand for electricity across the region. While the anticipated demand would be the highest seen this year, it would be in line with the ISO’s forecasts for the summer, and the ISO projects adequate supplies of electricity in the coming days.

Temperatures are expected to reach the upper 90s in Boston and Hartford, the region’s two largest centers of electric demand, on Tuesday, before tapering to more moderate temperatures later in the week.

As of Monday morning, ISO New England is forecasting the following peak electric loads:

• Monday, June 23: 23,920 megawatts (MW)
• Tuesday, June 24: 25,310 MW
• Wednesday, June 25: 23,130 MW

ISO New England’s system operators are well-trained to handle increased seasonal demand, unexpected generation loss, or transmission outages should they come to pass this week or any other day. System operators will continue monitoring conditions and have tools and procedures available to mitigate grid concerns if needed.

For more detailed information, visit the Seven-Day Capacity Forecast page.