Understanding the Paradox: Why Do People Drink Coffee in the Heat?

October 8, 2025 •

4 min read

Paradoxically, a study by the University of Ottawa found that drinking a hot beverage can result in a lower amount of heat stored in the body, which is a key reason why do people drink coffee in the heat. This effect is triggered by an increased sweating response, which can provide a powerful cooling sensation through evaporation.

Quick Summary

A hot coffee or tea can surprisingly induce a cooling effect by triggering the body's natural sweating mechanism. This process of evaporation helps dissipate body heat, providing relief in dry heat conditions. Moderate consumption is key, as is understanding the nuanced impact on hydration.

Key Points

Evaporative Cooling: Drinking hot coffee in dry heat triggers sweating, which cools the body as it evaporates from the skin.
Myth of Dehydration: Moderate coffee intake is not significantly dehydrating because the water in the beverage offsets caffeine's diuretic effect.
Sustained Energy: In heat, coffee can combat fatigue and sluggishness by providing a caffeine boost, aiding focus and energy levels.
Lower Acidity: Cold brew coffee is less acidic than hot coffee, making it a gentler option for sensitive stomachs in the heat.
Antioxidant Source: Both hot and cold coffee contain beneficial antioxidants, which can contribute to overall health benefits.
Hydration Practices: It is crucial to pair coffee with plain water during hot weather to maintain proper fluid balance.

The Scientific Thermoregulation Response

At first glance, drinking a steaming cup of coffee on a hot day seems counterintuitive. Our instincts tell us to reach for something ice-cold to combat rising temperatures. However, there's a surprising physiological reason behind this practice, and it's all thanks to the body's built-in air conditioning system: sweating.

When you consume a hot beverage like coffee, specialized nerve receptors in your mouth, tongue, and stomach register the increased temperature. This signals the brain that the body is overheating, prompting a powerful thermoregulatory response. The brain then tells the body to sweat more profusely. As this sweat evaporates from the surface of your skin, it draws heat away from the body, creating a significant cooling effect. This evaporative cooling can actually lead to a net cooling effect that surpasses the small amount of heat added by the hot liquid itself, provided the sweat can evaporate effectively.

This phenomenon explains why many cultures in hot climates, such as in parts of Asia and the Middle East, have long traditions of drinking hot tea or other warm beverages to stay cool. It is a natural and effective method, though perhaps less comfortable for those who prefer to avoid sweating.

The Role of Caffeine and Hydration

A common concern associated with drinking coffee in hot weather is the risk of dehydration due to caffeine's diuretic properties. While caffeine is a mild diuretic, meaning it increases urine production, this effect is often overstated, especially with moderate consumption. Research has consistently shown that the water content in a cup of coffee is enough to offset the diuretic effect, making it a viable source of daily fluid intake.

For regular coffee drinkers, the body develops a tolerance to caffeine's diuretic effect, further diminishing its impact on hydration. The key, as with any beverage during a heatwave, is moderation and ensuring you are also drinking plenty of plain water throughout the day. Experts suggest alternating between coffee and water to maintain proper fluid balance.

Other Benefits of Summer Coffee

Beyond thermoregulation, there are other reasons coffee drinkers stick with their routine, even in the heat:

Energy Boost: The summer heat and longer days can lead to increased fatigue. The caffeine in coffee is an effective stimulant for staying focused and energetic.
Headache Relief: Some people experience headaches in hot weather, and caffeine can help by narrowing blood vessels and restricting blood flow, which may relieve throbbing pain.
Rich in Antioxidants: Coffee is a rich source of antioxidants, which are beneficial for fighting free radicals and can help protect skin from UV damage, though it is no substitute for sunscreen.
Maintains Routine: For many, coffee is a cherished ritual that provides comfort and structure, regardless of the temperature outside. The pleasure derived from the aroma and flavor can be a mood-lifter.

How to Enjoy Coffee Safely in the Heat

To get the most out of your coffee without compromising your health in hot weather, follow these simple guidelines:

Stick to Moderation: The safest approach is to limit yourself to a couple of cups a day to avoid excessive caffeine intake, which could increase fluid loss.
Pair with Water: For every cup of coffee you drink, follow it with a glass of water. This is the most effective way to ensure you stay properly hydrated.
Mind the Add-ons: Many popular cold coffee drinks are laden with sugar, syrups, and creams, turning them into high-calorie, sugary beverages. Opt for black coffee or use low-sugar alternatives to avoid unnecessary calories and a potential sugar crash.
Time Your Intake: Consider drinking coffee during the cooler parts of the day, such as early morning. This avoids adding extra heat to your system during the peak heat hours.

Hot vs. Cold Coffee: The Physiological Impact in Heat

While the concept of hot coffee cooling you down through sweating is compelling, the choice between hot and cold depends on your priorities and tolerance. The following table compares the different effects of hot and cold coffee in the heat:


Aspect	Hot Coffee	Cold Coffee
Cooling Mechanism	Triggers sweating, leading to evaporative cooling. Works best in dry heat.	Provides immediate, momentary cooling due to cold temperature. Effect is short-lived.
Acidity Level	Higher acidity, which can be irritating for some with sensitive stomachs or acid reflux.	Lower acidity, especially with cold brew, making it gentler on the digestive system.
Caffeine Release	Absorbed more quickly, providing a rapid energy boost, but potentially leading to a faster crash.	Often provides a more gradual and sustained release of caffeine, offering longer-lasting energy.
Hydration Impact	Contains water, which offsets the mild diuretic effect of caffeine. Must be paired with extra water.	Similarly contains water. Can feel more refreshing, but still requires mindful hydration with plain water.
Antioxidant Content	May have slightly higher antioxidant levels due to hot water extraction.	Still a good source of antioxidants, though potentially less than hot brew.

Conclusion: Making an Informed Choice

The question of why do people drink coffee in the heat? reveals a fascinating mix of physiological science, personal habit, and cultural practice. The primary reason is the body's thermoregulation; a hot beverage can trigger a sweat-induced cooling effect, making it a surprisingly effective way to cool down in dry heat conditions. The myth of coffee being significantly dehydrating is largely untrue for moderate consumption, as the water in the beverage compensates for caffeine's mild diuretic action. However, responsible hydration remains crucial. Ultimately, whether you prefer your coffee hot or cold in summer comes down to personal comfort, taste, and how your body responds. By understanding these nuances, you can continue to enjoy your favorite brew in any season, making choices that prioritize your well-being. For those looking for more guidance on healthy eating habits in general, the Academy of Nutrition and Dietetics offers valuable resources for all seasons.

Frequently Asked Questions

Yes, drinking coffee in hot weather is safe for most healthy adults, provided it's done in moderation. It is important to also drink plenty of water to stay properly hydrated and counteract the mild diuretic effect of caffeine.

Yes, in dry heat conditions, a hot beverage can have a net cooling effect. It works by stimulating thermosensors in your body, which prompts an increase in sweating. As the sweat evaporates, it cools the skin and lowers your core body temperature.

Moderate coffee consumption does not cause significant dehydration because the water in the drink counteracts the mild diuretic effect of caffeine. However, in extreme heat where you are sweating heavily, it's always best to supplement with plain water.

Cold coffee, particularly cold brew, is generally less acidic than hot coffee and is often easier on the stomach for people prone to acid reflux or digestive issues.

If you are particularly sensitive to caffeine's diuretic effects or its stimulant properties, or if you consume large quantities, switching to decaf is a good option. For most people, moderate caffeine intake is not an issue.

To get the most out of your coffee, drink it in moderation, pair it with plenty of water, and opt for black coffee or use low-sugar additions to avoid extra calories. Consider enjoying it during cooler parts of the day.

This practice leverages the same principle as drinking hot coffee. Hot beverages trigger a thermoregulatory response that increases sweating, and the evaporative cooling effect helps the body to cool down in high ambient temperatures.