When extreme heat hits, people turn to AC, but what if the grid fails? From France to the US, heat waves are pushing power systems to the limit, raising blackout risks and energy prices when electricity is needed most.

The heat wave threatens to overwhelm U.S. grids and may force some to change their plans on one of the busiest travel weeks of the year.

During extreme heat waves, power grids are more vulnerable to outages. Experts and utilities said there are many ways people can reduce the energy strain.