Much of the upper Midwest and eastern United States is under a heat advisory, but surprisingly those areas aren't noticeably hotter than eastern Nebraska and western Iowa.
That's because the National Weather Service uses different standards for issuing the advisories and warnings, depending on the climate in a particular area.
Lower temperatures prompt a heat advisory in the Dakotas than they do in Nebraska, and in Nebraska than they do in the South.
The Quad Cities was placed under a heat advisory Friday because the heat index was expected to range from 98 to 105 degrees.
Omaha's heat index had been projected to reach 100 degrees Friday, but no such advisory was issued.
In Omaha a heat advisory isn't issued until the heat index reaches 105 degrees, said Barbara Mayes, meteorologist for the National Weather Service.
That's because the heat index is based on temperatures that a given population has become acclimated to, she said.
In the Sioux Falls, S.D., area, a heat advisory is issued when the heat index reaches 100 degrees, said Todd Heitkamp, meteorologist at the National Weather Service office there.
While Sioux Falls' weather isn't much different from Omaha's, its heat index reflects the needs of a northern population.
In Mobile, Ala., a heat advisory is issued when the heat index reaches 108 degrees, said David Eversole, meteorologist for the weather service there.
Noting that he was a graduate of the University of Kansas, Eversole said there's another interesting difference between Mobile and places like Omaha.
Mobile benefits from cooling ocean breezes. The highest recorded temperature at Mobile is 105 degrees, he said. That was set Aug. 29, 2000, and is based on records dating to 1842.
Omaha's record high is 114, set July 25, 1936.
Source: National Weather Service