Butler County will be under a heat advisory Friday, according to the National Weather Service of Pittsburgh.

The heat advisory will be in effect from 11 a.m. to 9 p.m. Friday, July 28.

The alert warns that hot temperatures and high humidity may cause heat illnesses.

The high temperature Friday is expected to top 90 degrees Fahrenheit, according to the National Weather Service. In Butler, the high temperature for Friday is forecast at 93 degrees.

However, the heat index may top 100 degrees, the weather service said in a Thursday alert.

The alert urged people in the affected area to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun and check up on relatives and neighbors.

Those working outdoors should schedule frequent breaks in a shaded or air conditioned area, according to the weather service alert.