The National Weather Service had a message for Arizonans amid the summer’s first extreme heat warning in Maricopa last week: hold off on the coffee. 

Now that temperatures are consistently in the triple digits, the NWS Las Vegas office issued a heat safety reminder in the form of a checklist. Among the helpful and well-known suggestions (drink water, wear lightweight clothing), they suggested another idea that was a bold betrayal for coffee connoisseurs: Lay off the java and caffeinated tea. 

We asked Maricopa residents if they were willing to give up their morning joe to stay hydrated.  

“Not as long as I have access to potable water,” said Senita resident Colette Heim. “I have two cups of coffee every morning. I’m just fine.” 

At the Dutch Bros drive-in on John Wayne Parkway, we asked those waiting in the balmy heat if they were if they were willing to heed the warning. It was “Can Cozy” day, so the wait was especially long.  

“Life is too short,” said Maricopa visitor Sharon Windsmith. “I’ll go in the pool if I’m too hot.”

Maricopa is expected to see high temperatures ranging from 109 to 113 degrees this week. The extended forecast shows daily highs in the triple digits, with extreme heat warnings listed under every single date from June 24 through July 3. 

Here’s the science: According to the Mayo Clinic, coffee is a diuretic. Put simply, it makes you pee more. To have any real effect, you need to drink 30 ounces of coffee, or 400 mg of caffeine per day to cause significant fluid loss. Caffeinated beverages like coffee and tea still count toward your daily fluid intake, but just plain old water is best to beat the heat.  

In other words, your iced latte can help keep you cool — but chase it with a glass of water.