Residents of Nebraska and Iowa probably don't need an advisory to inform them: It's hot outside. But the National Weather Service has issued heat advisories for both states, warning residents who venture outside to take it easy and stay hydrated in the oppressive heat. An excessive heat warning has been issued for the northeastern corner of Nebraska and northwestern Iowa — including Sioux City — with heat index values expected to rise to between 105 degrees (40.56 Celsius) and 110 degrees (43.33