Children, those with medical conditions, people who work outside and the elderly - all face a greater danger.
89-year-oldn Louis Turner lives with his son but spends most of the day home alone.
Up until this week, he was without an air-conditioner. Originally from Georgia, he says he doesn't mind the heat.
He has a heart condition and like many people with health problems the heat can be deadly.
Turner's home hospice nurse Erica Gravina says his home was oppressively hot and it was affecting his breathing.
"He can suddenly go bad, he is in a fragile state. He can become dehydrated or into congestive heart failure due to the overexertion of the heart in the heat," said Gravina.
Due to the risk, Gravina checks on Turner and her other patients more frequently.
Compassionate Care Hospice helped him get an air-conditioner which has proved to be vital.
"He is breathing better, his lungs are clear and he looks more comfortable. That's what we want for all our hospice patients,"said ???
Turner's family and friends are also checking on him. Health experts say if you have an elderly neighbor yourself that you should do the same.
Some early signs of trouble are fatigue, loss of appetite, feeling light-headed and nausea.
It is strongly suggested to drink water slowly, use a cool compress to cool down, and to stay in a place with air-conditioning.
If symptoms get worse or confusion or vomitting persists, then call 9-1-1 immediately.