What cocktails pair best with a heat dome?

Vasopressin, hydration, hangovers, and how to drink during a heat wave.

“Thousands of Texas Residents Warned Not To Drink Alcohol,” read an alarming headline on Newsweek’s website last week.

Did Robert F. Kennedy Jr.’s public health team make some startling new discoveries about tequila? Did plague-ridden armadillos fall into the Tito’s tank?

Turns out, the headline was lifted from a National Weather Service warning. Forecasts called for an unusually hot few days across large swaths of Texas, so residents were advised to stay away from margaritas, White Claws, Coronas, and, well, anything alcoholic. Similar advisories have been issued for parts of Arizona, Nevada, and California. As of this morning, the heat dome is moving into the Northeast and threatening to fell Gotham. (New York Times: “It’s About to Get Brutally Hot in New York City.”) At the time of this writing, 79,044,882 people were living under Extreme Heat Alerts, according to Heat.gov. Parts of Alaska were under a heat advisory for the first time in history. “Extreme heat” is fast becoming “another summer.”

The NWS warning about what not to drink was part of a boilerplate release. The no-drinks advisory was nestled in among other cautions: If you’re outside, take frequent breaks in the shade. Wear a hat or visor. Check on family and neighbors. Etc.

But journalism today needs Dateline: Armageddon to build “engagement,” and so reporters coax out the most alarming angle possible. In this case, it’s: no mojitos for you! Nor coffee, for that matter. My favorite recent alarmist headline? The Daily Mail: “Americans told not to drink coffee in three states: 'Lethal in a matter of minutes’”

But let’s look at the science of drinking during a heat wave.

The main reason to avoid alcohol in extreme heat is that alcohol is a diuretic. That is, it makes you pee more than normal. (The same goes for caffeine.) On your body’s hydration balance sheet, your outflow exceeds your input. Dehydration ensues.

Why? Your body constantly strives to maintain a balance between solids and fluids. One key mechanism is a hormone called vasopressin. When your cells or bloodstream get a little too chunky, your brain sends a vasopressin signal to your kidneys that says, “Yo, bro, ease up on the absorbing and discharging liquids thing.” Balance is maintained.

But alcohol essentially deactivates the vasopressin signal, and the message to the kidneys gets waylaid. Unaware of the impending fluid shortage, the kidneys keep the pump station open and liquid flowing. You end up dehydrated.

That’s the theory, although the details are still being worked out. Science being science, many people have been subjected to undignified experiments—generally involving controlled alcohol consumption and peeing in graduated cylinders.

The results? Not overly dramatic. And not entirely conclusive. Studies suggest that alcohol strength can matter—spirits prompt more urination than beer. A 2016 study found virtually no difference in pee production in those who drank either lager or still water four hours after pounding back glasses. Not too surprising, since beer is about 95% water. Hard spirits—roughly 60% water when consumed straight—tip the balance toward dehydration more quickly. A 2010 study found that in people who were already somewhat dehydrated, alcohol’s diuretic effect was diminished.

While science sorts these very important distinctions, researchers generally agree that chugging Aperol spritzes will dry you out faster in the heat than knocking back LaCroix.

If you ignore this advice, what risks are we talking about?

A human body is about 55%–78% water, depending on gender, age, and other factors. Dehydration begins when you lose 1% of your body mass to fluid loss. If you avoid anything containing liquid (including food), you typically lose about 1% in 13 hours, 2% in 24.

Dehydration is rarely fatal in the developed world, where safe water is freely available. Dehydration makes you terrifically thirsty, which triggers your brain to instruct your feet to head to a 7-Eleven to overpay for a bottle of purified water.

Drying out may not be lethal, but it can have serious impact. Dehydration can result in a loss of cognitive and physical performance, as well headaches and fatigue.

And poor cognition can impair judgment. A sober person might decide that sitting outside in 104°F heat is sort of stupid and will retreat indoors. A person deep in their cups at a pool party might squint up at the blinding rays of the death star, and think, This isn’t so bad. And then they slowly roast into a desiccated shell.

Hot weather drinking can also lead to epic hangovers. While hangover science is also still evolving, dehydration and the after effects of alcohol overconsumption are thought to be separate mechanisms, with both leaving your feeling like crap. If you’re both dehydrated and hungover, it’s like a two-for-one special in misery. Staying hydrated while drinking can lessen the odds of your being reduced to a tureen of quivering aspic come morning.

Offering hangover-avoidance tips might not be as dramatic as screaming “You are going to die!” But it’s a message that can actually pass the straight-face test—and might actually encourage drinkers to be more self-aware when the entire nation has become a sauna.

If I were in charge of National Weather Service advisories, my release would read: “Dangerous Heat Approaching: Avoid Bad Hangovers. Don’t be an Idiot; Drink Inside Where It’s Air Conditioned, Fool.”

Weather service personnel interested in commissioning me to write warnings are invited to contact me by clicking below.