The North American Electric Reliability Corporation (NERC), the self-regulating authority that oversees the stability of the nation’s power grid, is warning that some parts of the country could see blackouts during the summer.

The NERC’s Summer Reliability Assessment said that a combination of extreme heat and severe droughts plaguing the Southwest could create a major strain on the power grid and force power companies to shut off the electricity.

“Industry prepares its equipment and operators for challenging summer conditions. Persistent, extreme drought and its accompanying weather patterns, however, are out of the ordinary and tend to create extra stresses on electricity supply and demand,” said Mark Olson, NERC’s manager of Reliability Assessments, according to CNN.

The agency said the Upper Midwest and southern states along the Mississippi have the highest risk of rolling blackouts this summer. In addition to the forecast of extreme heat, several older power plants have recently been decommissioned, leading to worries there won’t be enough energy to meet demand. Making matters worse, the region is still rebuilding from a tornado in December 2021 that knocked out a major transmission line.

There is an elevated risk of rolling blackouts in Texas, the Southwest, and the West Coast as a historic drought has hit the region. The drought has drained lakes and forced power companies to cut back on hydroelectric power generation.

The NERC did say that states in the Northeast should have enough power capacity to avoid rolling blackouts during the summer.