An excessive heat warning has been issued until 7 p.m. on Friday for most counties in Southeast Iowa. Heat warnings and advisories are issued when dangerously hot temperatures last over an extended period of time. High temperatures are expected to be in the mid-90s in Washington County this afternoon and Friday afternoon with high humidity predicted. Those two factors can cause widespread heat index readings from 105 to 110 degrees. The National Weather Service says that heat illness is likely during an Excessive Heat Warning if precautions are not taken. They recommend staying out of the sun as much as possible, staying hydrated, and staying indoors whenever possible.