A heat wave is still scorching much of the midwest and southern U.S.

The National Weather Service has issued heat advisories for 14 states from New Mexico to North Carolina.

"Heat stroke, heat cramps or heat exhaustion are likely with prolonged exposure and physical activity," the weather service said. "Take extra precautions if you work or spend time outside."

The high temperatures have caused residents to turn up their air conditioners, creating a record demand for electricity which in turn means higher electric bills.

Water bills also go up as homeowners try to keep their lawns green.

In Texas, rarely used power plants are being opened just to meet the electrical need.

Dallas County officials say at least 13 people have died from the heat this summer.

Some Oklahoma residents are being asked to set their thermostats higher to conserve energy as officials are trying to prevent rolling blackouts.

The hot weather is expected to continue through the weekend.