Residents of New York may be sitting in dark houses with no air conditioning this summer if hit by a heatwave, says the nonprofit that runs the state's electricity grid.

The group, the New York Independent System Operator said in a reliability assessment report that New York's reliability margins will be "the lowest ... in recent history," UtilityDive reported Friday. 

The assessment estimates that the grid will have enough power resources during normal weather, but the margin that accounts for heat waves is increasingly slim. 

The state's reliability margin has declined almost 80% since 2022. In 2019, Democrat Gov. Kathy Hochul signed the Climate Leadership and Community Protection Act, which forces the state to adopt 70% emissions-free electricity by 2030 and 100% by 2040. Virtually all of that is wind and solar farms, backed up by batteries. 

“This assessment reflects the challenges of the grid in transition — declining reliability margins, performance issues with aging generators, and an absence of new dispatchable resources,” Aaron Markham, vice president of operations at NYISO, said in a statement.

Dispatchable resources are primarily generators powered by coal, natural gas, hydroelectric and nuclear.