PINAL COUNTY, Ariz. — Editor's Note: The above video is from previous coverage of Lopez's sudden death. 

The Pinal County medical examiner has determined Florence High School freshmen Dyrell Lopez died of hyperthermia and dehydration. 

The teen unexpectedly died on Aug. 19. His family said he was walking from home to school. He was found unconscious about a half mile from school on Butte Avenue. 

Lopez's grandfather, Ron Joaquin, told 12 News at the time someone who was passing by saw the ninth-grader and attempted CPR, but it was too late. 

RELATED: Florence boy died while walking home from school, family says

According to the medical examiner's office, hyperthermia is a condition when the body's temperature is extremely above average and dehydration describes the loss of water. 

Florence teen dies unexpectedly, school counselors available for students

This August, several parts of Arizona experienced abnormally hot and dry temperatures, according the National Weather Service. 

RELATED: Florence teen dies unexpectedly, school counselors available for students

Students remembered Lopez with a small memorial near the spot where he was found lying unresponsive.