After last week’s extreme heat wave, the National Weather Service is forecasting relatively cooler temperatures over the Fourth of July across Arizona. But, doctors warn the operative word here is “relative.”

On Monday, forecasters predict the daytime high will drop to around 107 degrees across Arizona’s low lying desert elevations.

That five degree difference from last week’s highs formerly pushing the 120 mark can feel like a reprieve. But, Dr. Rebecca Sunenshine with the Maricopa County Department of Public Health said now is not the time to let down your guard.

“Eighty percent of the people who die from heat-related illness in Maricopa County died when it’s not an extreme heat warning," Sunenshine said.

It’s not the temperature that has as much of an impact, she said, “We’ve had deaths when it’s been as cool as 80 degrees.”

She said the killer is Arizona’s hot, dry air that evaporates your sweat, which is the first warning sign of heat exhaustion.

If you insist on being outside this weekend, she said look for several other symptoms.

“When you get a headache and you’re starting to feel dizzy and nauseated,” for instance, Sunenshine said, “get into the shade, drink some water and apply a cold compress.”

If the symptoms are confusion or at the point of passing out, she said, get that person to an emergency room immediately.