Montgomery County Coroner Walter Hofman said an 87-year-old man from Roslyn, Pa. died of heat stroke while working in his yard.
Hofman said the man's body temperature had risen to 102.9 degrees Fahrenheit.
He said heart disease and diabetes also contributed to the man's death.
According to Accuweather, yesterday's high temperature in the area was 91 degrees. The heat index, which takes into account the humidity, was 95 degrees.