It’s really hot in Texas right now. Many parts of the state are hotter than they’ve ever been at this time of year. In the coastal city of Corpus Christi, the heat index, a combined measure of heat and humidity, reached a shocking 125 degrees Fahrenheit, or about 52 Celsius.

That’s because a weather system called a heat dome is parked over Texas, Oklahoma and parts of Mexico. People are struggling, and one person may have died from the baking temperatures. And, there’s a lot of worry about the Texas electric grid.

That heat dome could stay in place until early July. It’s forecast to expand to Arkansas, Louisiana and Kansas. As people turn up their air-conditioners to stay cool, will the grids hold?