You may think you're doing everything correctly to keep cool.
But sometimes symptoms can arise before you even realize it.
Here is a breakdown of what experts want you to know:
After several long days of sizzling temperatures emergency room doctors say they're seeing more people than usual showing up at the hospital who've been beat by the heat.
"We had a firefighter, a few construction workers, theme-park employees and guests coming in with signs and symptoms of heat exhaustion," said emergency medicine physician Dr. Rafael Chavez at Providence St. Joseph Medical Center.
He reminds us that the prolonged extreme conditions will continue to take their toll on our bodies even as we see a few degrees of relief.
"Dehydration can catch up to people, especially if they're working outside or don't have air conditioning in their house or apartment," he said.
While 20 to 30 minutes in these blistering conditions can lead to rapid water loss, Chavez said patients with chronic conditions such as diabetes may feel the detrimental effects even faster.
"Because you have less water within your bloodstream and your blood sugar goes higher. And when your blood sugar gets higher, you urinate more sugar and more water. So you get more dehydrated. It's kind of like a vicious cycle," Chavez said.
A similar situation for those with chronic heart failure and anyone else who takes diuretic drugs.
"They're constantly a little bit dehydrated just to kind of keep fluid out of their legs and their lungs. So those people can get dehydrated really quickly," he said.
And it's not uncommon to even see heat exhaustion patients coming in from a day at the beach or the pool.
"They jump in the water. They think, you know, they're staying cool, but really they're outside in the heat. They're still sweating, they're still getting dehydrated," he said.
Another common mistake doctors are warning us about is when new parents take babies out in strollers and do something that may seem harmless but that can be very dangerous.
"Newborns can't sweat and they put blankets on top of the strollers and it's like leaving a kid in a locked car. It is dangerous and should not be done," said Dr. Diana Lev with Dignity Health Northridge Hospital Medical Center.
And while the general advice is not to exercise or walk your dog until late at night in triple digit temps, well even that's not recommended.
"Really right now, there's no relief from the heat. Even at 8:00 or 9:00 at night, it's still 90-plus degrees outside," Chavez said.
His advice is to head outdoors early in the morning. Again the name of the game is drinking water every 20 minutes, staying out of direct sun and being indoors in air conditioning if you can.