Blackouts could plague a number of states in the U.S. this summer, regulators warn, as a combination of drought, heat, potential cyber attacks, geopolitical conflicts and supply chain problems could disrupt the power supply, according to a grim new report from the North American Electric Reliability Corporation (NERC).

The regulatory body found that large swathes of the U.S. and parts of Canada are at an elevated or high risk of energy shortfalls during the summer’s hottest months.

The Midwest is at especially high risk due to the retirement of older plants, which has caused a 2.3% decrease in capacity from last summer, as well as increased demand, according to NERC.

In the Southwest, plummeting river levels may cripple hydropower production, the group warned, and in Texas drought-related heat events could cause extreme energy demand.

A NERC map shows all states in the western half of the continental U.S., including North Dakota, South Dakota, Nebraska, Kansas, Oklahoma and Texas are at least under elevated risk of energy shortfalls, with parts of the northeastern-most states under high risk.

(North American Electric Reliability Corporation)

Many states under the Midcontinent Independent System Operator (MISO), such as Arkansas, Louisiana, Michigan, Wisconsin, Iowa, Minnesota, Iowa, Illinois and Indiana are either entirely or partly at high risk.

“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. “Grid operators in affected areas will need all available tools to keep the system in balance this summer.”

In California, where all 58 counties are under a drought emergency proclamation, officials are already warning residents that more than one million addresses may go dark this summer due to an energy shortfall.

The drought hampers the state’s ability to harvest energy from hydroelectric dams – in 2021, for example, the state was forced to shut off hydropower generation at the Oroville Dam in Northern California for the first time ever.

Wildfires and forecasted hotter-than-normal temperatures are also projected to further strain the energy supply.

Energy officials in Texas, which is also under elevated risk, announced Monday that the state is expected to have “sufficient” capacity to meet peak demands under normal conditions. However, a combination of factors such as extreme demand, low wind and outages at production plants could lead to blackouts.

Over the weekend, just days before the Electric Reliability Council of Texas (ERCOT) said it expected to have enough power this summer, officials asked Texans to conserve power after unseasonably high temperatures created record demand.

Both Texas and California suffered widespread solar energy losses after grid disturbances unexpectedly knocked them off line.