Why Deserts Like the Sahara Are Scorching by Day and Freezing by Night

Not many people know that temperatures in the Sahara Desert can drop by as much as 24°C (43°F) overnight.

If you’re planning a day trip to the Sahara Desert in North Africa, you’ll want to pack plenty of water and sunscreen. But if you’re staying the night, you’ll also need a snug sleeping bag to keep warm — not something most people expect to bring into the desert.

That’s because the temperature in the Sahara can plummet dramatically once the sun sets, dropping from a sweltering average high of 38°C (100°F) during the day to a bone-chilling low of around -4°C (25°F) at night.

This extreme temperature shift begs the question: why do such dry deserts experience such severe fluctuations in temperature? And how do native plants and animals adapt to these intense changes?

The Science Behind the Swings: Sand and Moisture

The key to understanding desert temperature extremes lies in a combination of two simple but powerful factors: sand and humidity.

According to a 2008 report from NASA’s Jet Propulsion Laboratory in Pasadena, California, when sunlight hits the desert floor, the top layers of sand absorb the heat and release it back into the surrounding air. During the day, this radiation heats the air, sending temperatures soaring.

But once the sun sets, there’s no longer any incoming energy to maintain the heat. And because sand has a low heat retention capacity, it quickly releases the stored energy into the air, causing temperatures to drop drastically. Within a few hours, what was once blisteringly hot becomes frigid and cold.

However, this alone doesn’t account for such dramatic overnight cooling. The primary reason behind these extreme fluctuations is the lack of humidity in desert air.

In extremely dry places like the Sahara or Chile’s Atacama Desert, the amount of water vapor — or humidity — in the air is nearly zero. And that’s crucial, because water vapor acts as a natural blanket, trapping heat near the ground. In more humid regions, this “invisible blanket” keeps temperatures from dropping too rapidly after sunset.

Water also has a much higher heat capacity than sand. That means it takes longer to heat up, but once it does, it holds onto that energy longer, slowly releasing it back into the environment — keeping nighttime temperatures relatively stable.

In contrast, deserts lack that moisture buffer. Without water vapor to trap warmth, heat escapes quickly into the upper atmosphere, leading to sudden nighttime chills.

Life in Extremes: Adapting to the Desert's Thermal Whiplash

Despite this intense daily shift in climate, desert organisms — from reptiles to camels to cacti — have evolved remarkable strategies to survive.

According to Dale DeNardo, an environmental physiologist at Arizona State University who studies desert animals, the biggest survival challenge in the desert isn’t the temperature itself, but simply finding enough food and water.

Still, the ability to withstand thermal extremes is vital — and different organisms cope in different ways.

Cold-Blooded Champions: Reptiles

Reptiles, known for being the most abundant and diverse animals in deserts, are masters of thermal adaptation. As cold-blooded creatures, they don’t use internal energy to maintain a constant body temperature. Instead, they rely on external sources of heat.

Many reptiles are also small, which gives them an advantage: they can quickly take refuge in shaded crevices during the scorching daylight hours or snuggle up against warm rocks to conserve heat at night.

Warm-Blooded Giants: Mammals like Camels

Large, warm-blooded mammals like camels face a bigger challenge. Their size makes it impossible to escape the sun completely, and they can’t afford to let their body temperature fluctuate too wildly.

Camels have developed an ingenious way to handle this: they maintain a consistent internal temperature through layers of fat and thick fur. These insulating layers help block excess heat during the day and trap warmth during the night, acting like nature’s built-in thermostat.

Feathered Survivors: Desert Birds

Birds of the desert, on the other hand, depend on evaporative cooling to regulate their body temperature — similar to how humans sweat or dogs pant. This method involves using water to remove heat from the body.

Different birds have evolved unique techniques for this. Some vultures, for example, urinate on their legs to cool themselves down as the moisture evaporates — an unusual but effective survival trick.

Plant Power: The Most Vulnerable Survivors

Desert plants arguably face the toughest challenge of all. They can't run to shade or dig burrows. They’re rooted in place, vulnerable to every fluctuation in climate.

Iconic plants like cacti have evolved clever defenses to thrive in arid environments. These include spines, thick waxy coatings, and even chemical toxins — all designed to prevent water loss and ward off thirsty herbivores.

But while they’re well-adapted to heat and dryness, freezing temperatures are another story. When water inside plant tissues freezes, it expands. This can rupture cells and cause permanent, often fatal, damage.

As a result, desert plants typically grow only in areas where nighttime temperatures rarely dip below freezing for more than a few hours — a boundary known as the frost line. Beyond that line, survival becomes nearly impossible.

Conclusion: A Land of Extremes

The Sahara and other deserts are more than just endless dunes and burning sun — they’re landscapes of extremes, swinging between fire and frost in the span of a single day. The combination of sandy soil, clear skies, and dry air creates a perfect recipe for thermal volatility.

Yet despite this brutal environment, life endures. From tiny lizards that hide in shadows to mighty camels crossing the dunes, desert organisms prove that nature always finds a way to adapt, survive — and even thrive — in the most unforgiving places on Earth.