When will the heat end?

Dangerous heat continues to spread eastward this week, bringing the hottest temperatures of the year for many southern states outside of Texas.

“The full wrath of summer will grip the South this weekend,” forecasters in Atlanta warned Wednesday.

More than a dozen daily high temperature records could be broken across the region by the end of the week. But what’s even more dangerous is the record potential for what’s known as the high minimum temperature, meaning locations aren’t expected to see much lighting at night.

These high nighttime temperatures arise because the humidity prevents the air from cooling as efficiently at night. Moist air can also prevent the body from cooling down as efficiently, because the air is so saturated that moisture from a person’s skin has nowhere to evaporate, a necessity for cooling. Therefore, the heat index, which explains the combination of temperature and humidity, is an important measure of what the actual temperature feels like.

The highest heat index readings of 110 to 120 in the coming days are expected to affect people in the cities of Dallas, Houston, Jackson, Miss., Little Rock, Ark., Nashville and New Orleans.

But it’s not just the south: The heat is also affecting people from the southwest and across the southern plains.

As the high-pressure dome shifts to the east over the July 4 long weekend, some relief is expected. In parts of Texas, the Lower Mississippi Valley and the Mid-South, temperatures will drop to near normal levels this weekend, forecasters said. However, the dangerous heat will continue for those along the Gulf Coast, where humidity is expected to remain high.