FRESNO, Calif. (KFSN) -- The high heat can quickly lead to health issues if you're not prepared for it.
Emergency room doctors and paramedics have already been treating people this week for heat-related illnesses.
The priority during this heatwave is to try to stay cool and hydrated.
Paramedics and emergency medical technicians are responding to more calls due to the high temperatures.
American Ambulance Operations Manager Ben Garcia has seen a rise in cases of heat-related illness.
"People who are becoming over-heated, really active outdoors, they really haven't hydrated too much so they start becoming dizzy and maybe passing out," says Garcia.
Doctors say the best way to avoid heat illness is to drink plenty of water and avoid too much exposure outside.
"Minimize your alcohol consumption. That plays a big factor in becoming dehydrated," says Garcia.
Unfortunately, some people have needed to be taken to the emergency room.
"We're definitely seeing patients that have heat exposure, heat syncopy, heat stroke, various medical terms for various forms of heat illness," says Dr. Kenny Banh of CRMC.
Banh says those emergency room visits often involve people in high-risk groups.
"They're people that are very young, very old, don't have access, maybe some are elderly or people who are socially disadvantaged that don't have access to air conditioning or cooling areas."
It's always a good idea to check on family and friends to see how they're holding up in this heat.
Garcia says heat exhaustion can start with a headache and progress to something more serious.
"You develop dizziness, fatigue, lethargy. Heat stroke is a true, serious, serious life-threatening emergency where you develop an altered mental status."
Dr. Banh says people who work outdoors should be especially careful of becoming over-heated.
"Drink lots of water and take breaks even if you don't feel like you're overheated. If you're outside, whether it's for enjoyment or for work, take a break, get some AC, get a cool towel."
Dr. Banh can't stress enough the importance of drinking plenty of water, before you even start to feel thirsty.