An excessive heat warning is to take effect at 10 a.m. Monday and run through at least Wednesday. Meteorologist Chris Kuhlman of the National Weather Service explains how they determine when the heat is excessive.

"So the low temperature is high enough, we take the average between the low and the high and if that equals to be 100 degrees or warmer than we definitely consider that to be excessive heat," Kuhlman said.

Kuhlman says temperatures this week will warrant the excessive warning. But, he says the humidity should be a little lower this week than it has been.

The hot, humid conditions of the Arizona monsoon make it difficult to get outside and keep an active, heart-healthy lifestyle. Chrissy Spoo with the American Heart Association says that may mean you need to cut back on your physical intensity for a while.

"Look at the weather forecast and maybe plan your workouts and plan your outside activity for the cooler parts of the day, preferably when the sun is not so hot, so early morning," Spoo said. "The other thing is to decrease your intensity and duration at high temperatures or a high humidity level."

Spoo says when you get ready to resume workouts, after scaling back during the excessive heat and humidity, you need to take it slow and not go wide open right away.